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RE: Max. Operating Oil Temps. and Oil Coolers

NORTY — Mon, 14 Jun 2010 14:16:31 GMT

Yes, oil temps of 250F are ok. The "rule of thumb" for oil temps is this~

For every 10 degress F > 250F, you lose 50% of your oil life. This is caused by additive destruction, not whether the basestock is syn, semi syn or "dino."

RE: Max. Operating Oil Temps. and Oil Coolers

deadman — Mon, 15 Feb 2010 08:47:52 GMT

sgtslag (2/14/2010)

You make some valid points, Deadman. After thinking about it, I realized that an oil cooler on a touring machine, pulling a trailer, would be an excellent idea. My car has a transmission oil cooler on it, from the factory, which really makes a difference if towing a trailer. I've been told that a transmission oil cooler is something that should be required on all vehicles (cars/trucks) towing trailers, if you want to avoid replacing your transmission in the near future...

Most touring bikes are water cooled, but add up two riders, full saddlebags, a full trunk, a full tank bag, and a trailer loaded down, besides, and I can see the water jacket being insufficient! I had never really given it much thought until I read your comments. In my textbook on motorcycle mechanics, the topic of cooling was primarily discussed from a 'troubleshooting the system' point of view. There was no discussion of the system being overloaded in any way. I was actually disappointed in the whole topic in the book, but it was focused towards one approach, so I can't fault it.

Thank you for taking the time to correct me, and prevent me from spreading false information. I appreciate it. Cheers!

No problem man, and keep in mind: Oil coolers and transmission oil coolers are different items. Manual transmissions(in cars or bikes) very rarely generate enough heat to need cooling(one exception might be oval track racing). Automatic transmisions all require one, and all come with one to start with -usually built into the radiator. What you're referring to is an auxilliary transmission cooler, which is an add-on, highly efficient cooler to help abate the tremendous heat generated in an A/T during towing/hard use.

RE: Max. Operating Oil Temps. and Oil Coolers

sgtslag — Sun, 14 Feb 2010 10:47:17 GMT

RE: Max. Operating Oil Temps. and Oil Coolers

deadman — Sat, 13 Feb 2010 22:17:48 GMT

sgtslag (2/13/2010)

Deadman, now you have me curious. The water jacket usually covers the cylinder block, as well as the crankshaft portion of the engine; I don't remember if they cover the transmission at all, or not. Are you referring to M/C engines, or are you thinking of car engines? It's normal to have separate oil coolers on transmissions, and power steering pumps in cars, but I've not heard of oil coolers on water cooled motorcycle engines before, outside of racing. I'm all ears though, as you can never know too much. Cheers!

M/C or auto...doesn't matter -the principles are the same. Part of the oil's job is cooling parts not able to be water-cooled effectively(valvesprings, rockers, cams, crankshafts, pistons, etc). That superheated oil drains down into the pan/sump and it continues to maintain that heat as a natural property of oil is thermal stability. It may cool somewhat as it runs down the inside of a watercooled block/case, but that minimal cooling effect is easily overcome...especially if one considers laminar flow and if the cooling system is set to maintain a temp of 210d to start with.

There's a difference between an oil cooler, and a transmission oil cooler. Transmission oil coolers are usually only required for A/T vehicles due to the intense heat generated by the shearing forces at work inside their torque convertors. They are unrelated to this discussion.

There are hundreds of water cooled autos that come stock with engine oil coolers. Just because there aren't many/any stock watercooled bikes that have factory oil coolers, doesn't mean: "With a water-cooled engine, an oil cooler is a waste: the water jacket cools virtually the same as an oil cooler, only more directly." That statement is flat wrong. Water cooling only affects oil temperature as a secondary effect...and one which can be easily overcome at that.

RE: Max. Operating Oil Temps. and Oil Coolers

sgtslag — Sat, 13 Feb 2010 20:39:29 GMT

RE: Max. Operating Oil Temps. and Oil Coolers

deadman — Sat, 13 Feb 2010 15:22:58 GMT

Not true sarge. Plenty of water cooled engines require radiators and oil coolers. As we all know, it's not uncommon to see oil temps much higher than coolant temps. If the cooling system is setup with say a 210d thermostat, the oil temp can easily exceed 250d under some conditions.

If the coolant thermostat is say a 160 or 180, it's fairly unlikely that oil temps would reach 250, but still possible none-the-less. In that case, the oil cooler may only be needed occasionally, but it's still needed.

RE: Max. Operating Oil Temps. and Oil Coolers

sgtslag — Sat, 13 Feb 2010 11:41:17 GMT

With a water-cooled engine, an oil cooler is a waste: the water jacket cools virtually the same as an oil cooler, only more directly. If you read my previous posts, you know that with the oil cooler functioning, my oil ran at 210° F (250° F without!) at the exit point of the oil pump. If you have a temperature gauge on your water cooled bike, you will note that the normal operating temperature is roughly 210° F...

An oil cooler won't gain you much, except that it will cool your engine twice as fast/efficiently -- thermostats would become even more critical, as you would not want them to become stuck open excessively cooling your engine! You really won't gain anything, except to add complexity, and increase the chance of failure of something -- unless you are talking about a bike used for track/drag racing.

With regards to running synthetic oils, they can handle higher temperatures much better, and longer, than dino-oils can. Dino-oils break down above 250° F, while full synthetics can handle temperatures in excess of 300° F before breaking down into sludge and carbon deposits. The spin-on oil filter will gain you some surface area increase, thereby cooling the oil a bit more. The water cooling system, however, is very sufficient for the engine's needs. Cheers!

RE: Max. Operating Oil Temps. and Oil Coolers

rnrkeeper — Sat, 13 Feb 2010 09:09:06 GMT

I am getting ready to install a Bergmen spin-on oil filter conversion kit on my '03 ZRX. I figure I will get some added cooling of the oil since the filter will be outside the engine sump area and will have access to some free flowing air. Since the ZRX is water cooled I have never worried much about the oil temperature other than curiosity. I have used since the engine was broken in Amsoil or Mobil MX4T synthetic or whatever it is called now. 3,000 miles max between changes. I have wondered if an oil cooler would be beneficial. It would have to be temperature regulated for sure since these synthetic oils maintain their viscosity much better than dino oil.

From what I have read, most engines discussed were air cooled and they surely need help in cooling. My '85 Nighthawk was built with a cooler and I am sure it has kept the engine in better shape. Does anyone have any water cooled engine data with oil coolers?

Ben Kirk

RE: Max. Operating Oil Temps. and Oil Coolers

rnrkeeper — Sat, 13 Feb 2010 09:08:20 GMT

Ben Kirk

RE: Max. Operating Oil Temps. and Oil Coolers

ibafran — Tue, 02 Feb 2010 17:49:01 GMT

sgtslag (2/2/2010)

I did let her know... She is writing for Kawasaki, so my classic Honda puts my wife and I out of the running for the article.

Ok. I re-read the thread. Although there is no reason for it, I somehow got the idea that you had a Kaw Z-1. And so it goes...

750 Hondas are even easier to work on than the Z-1. And there are a lot of guys in speed shops with lots of experience with them to this day.

Maybe, shortinseam will use us for background, resource, and generic material?

RE: Max. Operating Oil Temps. and Oil Coolers

sgtslag — Tue, 02 Feb 2010 14:25:31 GMT

I did let her know... She is writing for Kawasaki, so my classic Honda puts my wife and I out of the running for the article.

RE: Max. Operating Oil Temps. and Oil Coolers

ibafran — Tue, 02 Feb 2010 14:03:21 GMT

sgtslag (2/2/2010)

Thanks, Ibrafan. I love my bike. ... !

That is a nice bike as I have said. If you have a co-rider or passenger with you on that bike at times, I think Shortinseam will want to know about it. PM her in her "Couples" thread.

RE: Max. Operating Oil Temps. and Oil Coolers

sgtslag — Tue, 02 Feb 2010 08:55:54 GMT

Thanks, Ibrafan. I love my bike. I could save up, and get something newer, but I really love the style, size, etc. I've got it close to fitted out to what I want (accessories, doo-dad's, etc.), as well. I am currently studying the motorcycle mechanic textbook, and I do light mechanic work myself. I just don't have the tools, or the expertise, to do an engine tear-down. Unfortunately, serious engine work would have to be done by a shop.

As far as what wears out at 70k, I don't really know (cam chain, piston rings, valves?). I am very proactive at maintenance, and I plan on changing the oil more frequently, even with an oil cooler, to lengthen the longevity. My bike is not for collecting, it is for riding (1,935 mile tour around Lake Superior last Summer, plus weekend day trips of 200-300 miles many weekends), but I still take as good a care of it as I can. Time will tell all. Cheers!

RE: Max. Operating Oil Temps. and Oil Coolers

ibafran — Tue, 02 Feb 2010 03:30:08 GMT

sgtslag (2/1/2010)[hr ... My bike has a reputation for the engine lasting 70k+ miles (currently have ~20k miles on it), ...

What part of the engine wears out at 70k miles? Aftermarket pistons and rings are not cheap but are readily available. A good machine shop will bore the cylinders for not a lot of money. If the valves are not tulpiped or seats sunk, a hand lapping will bring them up to snuff. If the valves are tuliped , it is a good time to upgrade to modern metals. Aftermarket valves and seats should be available. That info could be sourced from owners groups. A good chunk of change can be saved if you are willing to do the disassembly and reassembly yourself. Its a great bike and fairly easy to DYI in that capacity.

Be grateful that you have such a nice usable bike from the era. HD owners from the era usually have to freshen the top end at 25-35k miles and the bottom end at 50k miles.

RE: Max. Operating Oil Temps. and Oil Coolers

deadman — Tue, 02 Feb 2010 00:55:02 GMT

hallowedcontactpatch (2/1/2010)

I am perplexed as to how the oil temp at rcneilsen's filter could be 50 degrees higher than the sump. The oil from the sump would be pumped directly to the filter before travelling through the rest of the engine. Unless the location of the sump versus the drain location is the main factor.

My guess would be the cooling of the finned sump itself, and how the sensor was mounted in the drain plug...it may have been better at picking up the temp of the aluminum sump itself, than the oil in it.

RE: Max. Operating Oil Temps. and Oil Coolers

hallowedcontactpatch — Mon, 01 Feb 2010 09:09:57 GMT

RE: Max. Operating Oil Temps. and Oil Coolers

sgtslag — Mon, 01 Feb 2010 08:34:18 GMT

Cleverboy is correct. My goal in using an oil cooler, is to lower the average oil temperature, throughout the system, to extend the life of the oil, and the engine. My bike has a reputation for the engine lasting 70k+ miles (currently have ~20k miles on it), but I would like to extend it further (not worth investing a lot of money to overhaul it due to age and parts availability/cost -- a 1979 bike). My educated guess is that an oil cooler, with a thermostat, will do the job. However, I have no information as to how long an oil cooler will extend the life of the engine.

I appreciate the input from everyone. It helps to understand the overall issues, and how to interpret the results (especially the temperature readings from the various locations all being different). Cheers!

RE: Max. Operating Oil Temps. and Oil Coolers

cleverboy — Mon, 01 Feb 2010 07:34:20 GMT

It's always hard to find an end all be answer to your questions because there is no one size fits all answer.

Understand that when you measure your oil temperature, you are measuring the "average temperature usually in an oil gallery just post oil cooler and oil pump, but without any load on the oil." If you could measure the oil temperature when it is under stress, say in a camshaft/lifter interface, you would find that the spot temperature is much higher than the average temperature, but only for a micro second, then the oil mixes with other lower temperature surrounding oil and averages out.
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Oil will oxidize/degrade at room temperature, only the reaction rate is very slow. As the temperature and pressure increases, the reaction rate increases, especially when the average oil temperature gets above about 250°F for any length of time. The longer oil stays hotter the faster it generally degrades.

RE: Max. Operating Oil Temps. and Oil Coolers

trauscher1 — Sun, 31 Jan 2010 20:36:03 GMT

rnielson:

That's kind of interesting--two sensors--one gauge. I installed a sensor in the sump of my KZ1000, air cooled. At first, I thought the gauge was defective because the needle stayed on the peg below 140 degrees. I had to test it in boiling water--sure enough when the water boiled, the gauge read 212F. The gauge was good, the oil just runs very cool. It takes about 20 miles of highway riding with ambient temperatures around 60F or better to get the oil temp up to 180F. Head temperature is another thing. Using an infared thermometer, head temps usually are over 300F. Who cares? The bike gets a valve job about every 80,000 miles and has over 300,000 on it now. I may know what the oil temperature is, but I don't think it makes any difference to the bike!

RE: Max. Operating Oil Temps. and Oil Coolers

rnielsen — Sun, 31 Jan 2010 15:56:03 GMT

Measuring oil temps can be confusing. On a 1982, GS650 Suzuki I had two temperature sensors with a switch to select one or the other for the gauge. One was screwed into the oil filter cover plate on the engine front where oil from the pump entered the filter. The other was in the drain plug in the oil sump. No oil cooler was used.

I found oil temps took a long while to reach maximum, 18-25 miles on a fairly hot day. Then the sump temperature was about 40-50 degrees lower than the oil coming into the filter housing from the oil pump. Apparently the cooling fins on the sump were effective.

Oil temps usually ran 250 - 260 at the filter and 210 - 220 in the sump. Based on that I felt that non-synthetic oil was adequate.

Modern synthetics have flash points over 400 degrees, which is the point where they begin to burn. I doubt that temp is reached, even under extreme conditions.

Ray Nielsen, happier now with synthetics!

RE: Max. Operating Oil Temps. and Oil Coolers

sv650 — Sat, 30 Jan 2010 17:38:24 GMT

Thanks for clearing it up for me. I now understand your setup.

RE: Max. Operating Oil Temps. and Oil Coolers

sgtslag — Sat, 30 Jan 2010 16:58:35 GMT

Sorry for the confusion. Yes, a thermostat (I have a Perma-Cool unit) automatically bypasses the cooler/radiator until the oil reaches 180°F, then it opens a valve and pushes the hot oil up to the radiator.

With regards to the oil temperature sensor, it is screwed into the filter/cooler adapter, attached to the front of the engine block, just behind the front wheel. The oil flows past/around it, within the adapter's internal cavity.

I had issues on the day I ran it from Minnesota to Iowa, and I had to disconnect the cooler hoses, and put a short, bypass hose onto the adapter, to keep the oil leak from killing us (oil was dripping onto the road, in the path of the rear tire -- we stopped before it got bad enough to cause an accident).

Here is the interesting part: oil was leaking from the hose barbs, as the normal hose clamps weren't strong enough to prevent oil from seeping around the barb. I looked, but I could not find stronger, T-bolt clamps that would fit around a 1"/25mm OD hose (the size on the radiator side of the thermostat). I found, and used, high pressure hose clamps for fuel injection systems (40+ PSI, typically), up to 16mm OD hoses, and that worked for the engine side of the adapter (I used a 16mm OD hose on that side, by luck, not really design), and the thermostat. The sizes for T-bolt clamps jumped from 16mm to 2-1/2" and up to around 8"! I could not find any US seller offering a 25mm T-bolt clamp...

I finally found some 25mm T-bolt clamps in Britain, and Australia (manufactured in Germany!). Go figure (I decided to try searching the metric size, since I came up with nothing using 1" as my search parameter). I plan to retry the cooler this Summer, with the new clamps. I love the idea of an oil cooler, with a thermostat, but it has to work without leaking. I'm difficult that way.

If your engine oil runs below 250°F, you really don't need an oil cooler. Unfortunately, my engine runs at 250°F, which is the upper limit of dino-oil's operating range. Above that, according to the textbook, it breaks down to carbon deposits, and varnish. My hope is to keep my oil running between 180°F, and 210°F, if I can. We're going to be riding two-up, pretty much all the time, so an oil cooler will help reduce the engine strain, and heating. Besides all of that, it is just fun to wrench on an oil cooling system to the bike. Cheers!

RE: Max. Operating Oil Temps. and Oil Coolers

deadman — Sat, 30 Jan 2010 08:32:27 GMT

sv650 (1/30/2010)

Sarge, I am confused, as usual. You say on your test runs, with the oil cooler running and oil cooler not running. Do you have a way to by-pass the oil cooler in order to turn it off? As you say the oil flows through the cooler and then the filter to the engine. With a thermostat in the flow would this not cut out oil flow until the pre-set thermostat temperature is reached thereby starving the engine of oil? Like I said I am confused, probably just another senior moment.

I have run Rotella syn. oil in my bike since the first change at 500miles. I have no way to check my oil temp. don't know if they make a gauge that would go into the oil fill port. The bike came with a factory oil cooler.

Oil cooler "thermostats" are actually thermostatic bypasses. They either allow oil to pass through to the cooler, or re-route it to bypass the cooler.

That's a manual bypass, a thermostatic one does the switching for you.

RE: Max. Operating Oil Temps. and Oil Coolers

sv650 — Sat, 30 Jan 2010 06:07:28 GMT

RE: Max. Operating Oil Temps. and Oil Coolers

jerseyjim — Sat, 30 Jan 2010 04:27:08 GMT

My '76 Shovelhead had an oil cooler...I think the brand was "Lockhart". Not hard to install as I remember. An oil cooler for this motor was definately recommended (remember, this is back in the day of straight 60W...and even that blew thru a quart every 500-700 miles....

There was an optional "thermostat"...but a simple cut-to-size piece of plexiglass tie-wrapped on kept the oil from getting TOO cool during the winter months. Yes..oil getting TOO cool is not the best thing for any motor.

My '92 EVO...the dealer said when I bought it (new, in '92) and years later still claimed an oil cool was not even recommended...in my climate. Thru Death Valley...yeah. But not in beautiful downtown NJ.

So..to this day, I have no oil cooler on the EVO. The thermometer I have on the oil dipstick has never read above 210...on a 95 degree day....(usually stays around the 180 degree mark on average) and that is, I think "normal" for a stock EVO motor.

All that said, I had oil coolers on a couple of my mid-1970s Honda SOHC 750s......I donno...Generally, I think oil coolers can do no harm...as long as a thermostat is there to control the temperature.

RE: Max. Operating Oil Temps. and Oil Coolers

deadman — Sat, 30 Jan 2010 00:16:36 GMT

Good stuff Sarge.

I agree that the 30d figure is just silly. Cooler size/design/airflow/air temp/oil flow volume/etc, all play a part. And thinking that the front cyl would heat up from it is just overly simplistic.

Aside from the pat on the back, the only thing I'll add is there is no break year when synthetics become a good or bad idea. Old motors use oil too, and they'll benefit just the same.

Max. Operating Oil Temps. and Oil Coolers

sgtslag — Fri, 29 Jan 2010 13:20:41 GMT

Last Summer, I posted something in a thread about the maximum operating temperature for mineral/dino-based oils as being 250ºF, and someone asked where I got that number from. Currently, I am studying "Motrocycles: Fundamentals, Service, Repair", by Bruce A. Johns, David D. Edmundson, and Robert Scharff, ISBN 1-56637-4790. I happened across this from Chapter 10: Lubrication Systems, page 239:

"Normal maximum engine oil temperature is considered to be 250ºF (121ºC)."

Now we all have a reliable source to reference for this tidbit, for our fun discussions on oils.

However, a couple of lines above that, these same authors state, "An oil cooler is a most efficient means of cooling engine oil. It can reduce oil temperatures up to 30º." (Emphasis mine.)

I take issue with this statement, as I measured a cooling effect of 40º on my bike. It is also interesting to note that many folks lament the fact that people put oil coolers in front of their upper cylinders, which means the hot air from the cooler will blow directly onto the upper cylinder area, causing it to heat up, defeating the purpose of cooling said engine.

On my bike, I had a temperature sensor which was bathed in hot oil coming out of the pump/engine block. From that point, it flowed up to the cooler/radiator, then down to the filter, and back into the engine. My oil temperatures ran 250ºF without the cooler running, with an ambient temperature of 77ºF, riding two-up, saddlebags and trunk loaded, running 60 MPH on the highway, for over two hours, with the temperature reading remaining constant. With the cooler running, located six inches in front of the upper cylinder head, blowing its hot exhaust onto the head (same riding conditions/load, same road, but an ambient temperature of 87ºF!), the oil temperature reading remained constant at 210ºF!... My radiator was from a CB900, and my bike is a CB750, so the radiator is likely a little larger/more BTU's than what is required for my engine. Note that I also installed an oil thermostat, to bypass the radiator until the oil reached 180ºF, to allow the oil, and the engine, to reach operating temperature.

Two things of note: 1) an oil cooler can cool oil beyond a mere 30º -- it depends on the size of the radiator, engine, oil capacity, etc.; 2) placing the oil cooler/radiator directly in front of the upper cylinder, or any other engine portion, won't adversely affect the engine's cooling (modern, water-cooled engines always locate their radiators in front of the engine block! Why would an oil cooler be any different?), besides, the upper cylinder, where combustion takes place, is likely much hotter than 210ºF anyway, so air blowing across it at 210ºF is still going to cool the upper block.

If you run synthetic oil, the max. op. temp. I found months ago, on the Internet (the textbook doesn't touch on synthetic oils...), was 300ºF, or possibly higher. This would suggest that if you have an air-cooled engine, newer than 1980 (roughly, based on what I've found on the Internet...), you might want to run synthetic oil, as it may run at 250ºF, causing dino oil to break down faster. Cheers!