Oil Temperature -- From Engine vs. From Outside

[TucsonDon]

It hit 105 today in Tucson, or so my thermometer said. Each year as summer approaches I wonder about the effect of the outside air temperature on the temperature of the oil in the engine.

My bike is an '07 Goldwing, which is water cooled. The cooling system works just fine -- the temperature gauge is consistently just below 1/2, and the fan comes on only occasionally.

Here's my question -- I hear about the effect of "extreme heat" on oil, and I wonder what exactly that means ... particularly for a water cooled bike operated normally -- that is, no excessive idling in traffic, no towing a trailer, no aggressive redlining of the tachometer.

My guess is my oil temperature -- whatever that is (the Wing does not have an oil temperature indicator) -- doesn't really vary that much, be it 90 degrees outside or 110 degrees outside. My guess is as long as I'm moving down the road and the air is flowing through the radiators (yes, plural ... there are two of them), my oil temperature probably stays relatively stable, and below "extreme."

And my ultimate question is this -- Is there any reason to believe Tucson summer heat really calls for a synthetic? Or would a good, modern conventional oil do just fine in a water cooled bike in the Tucson summer?

 

[paul246]

There is no doubt that the Goldwing flat six has a more than capable cooling system. The oil temperature will spike, however, on occasions such as motoring down the freeway on a hot day and then taking an off-ramp into slow moving city traffic. It takes a while to get rid of the heat build up and the oil temp will rise sharply during that time.

 

[wileyE]

. The only time you ever really see a manufacture synthetic recommendation it's usually an optional thing about low winter temps. For hot summer temps they move you up to the next viscosity.

You wing is probably on 10w30? maybe put it on a 40w when its hot.

Even if a syn 10w30 held up to the heat better, it's still going to be running thinner than grade when really hot just like your mineral 10w30 would. So, being syn isn't a substitute for correct grade.

Will the syn survive the heat better to ride another day? In theory yes, in reality??? not like it should.

 

[TucsonDon]

Originally Posted By: wileyE
You wing is probably on 10w30? maybe put it on a 40w when its hot.

Yes, it specs a 10W-30, but allows 10W-40 for temps above 80. I run a 40-grade year round. I never start my bike in temps less than about 40 degrees, so I wouldn't really take advantage of the cold-flow properties of synthetic.

I asked the question because I was reading the "Ask the Expert" section of the Rotella forum, and for the question "Why choose synthetic oil for my engine?" the answer was:

At high temperatures, synthetics are more oxidation resistant and less volatile than mineral oils. Less volatility can be a benefit, because less oil will be lost by evaporation, so you may not have to top-off oil as frequently. High temperature oxidation resistance isn't always a benefit, because many older diesel engines don't get hot enough to really challenge mineral oils that contain antioxidants.

I've never had to add oil to the Wing. Near as I can figure, it simply doesn't burn or lose oil at all. And I suspect my Wing is like "many older diesel engines" in that it simply doesn't get hot enough to really challenge a good quality mineral oil.

Oh, and my OCI's average around 3K miles.

 

[Steve S]

What is the temp of the oil on the hottest days or at the highest load. And a real good indication of heat is the oil pressure drop .

 

[TucsonDon]

Originally Posted By: Steve S
What is the temp of the oil on the hottest days or at the highest load. And a real good indication of heat is the oil pressure drop .

The Goldwing has no oil temperature indicator. And it has no oil pressure gauge ... only an indicator light. So without after-market probes, I can't know those two things.

 

[sunruh]

and the worst part is you probably dont know where the idiot light comes on at either! and i'll guess at 10psi or less!
don, try to find out at what psi the id10t light comes on at.
no doubt about the heat being a real test for you boys.
was 100+ both days here this weekend. pool was very nice!

 

[02zx9r]

went dirtbike riding yesterday, was ok when riding with the vented jersey/pants but stopped taking a break man it was hot, but still a good time like always

 

[dnewton3]

TusconDon -

In response to your ULTIMATE question:
Yes, a conventional oil will do fine. I choose to use HDEO diesel marketed oils such as Rotella, Delo and Delvac for use in my 2006 GL1800 ABS. Excellent packages that allow for great performance at a good price.

Think about the heat issue for a moment. Your liquid cooled GL1800 won't get the oil any hotter than the oil that circulates into and around a turbo on a diesel truck. And there are plenty of dino-based HDEO's that show great UOA protection in that hot-oil environment.

Synthetics do handle extreme temps better; this is true. But by extreme, I mean E X T R E M E. Like -20 degF for cold starts, or "Oops - Honey, the temp gage is in the red and steam is coming from under the hood". Normal operating temps, around 190-210 degF, are perfectly acceptable for conventional oil.

 

[TucsonDon]

Originally Posted By: dnewton3
Yes, a conventional oil will do fine.

I thought so ... looking for confirmation!

Originally Posted By: dnewton3
Your liquid cooled GL1800 won't get the oil any hotter than the oil that circulates into and around a turbo on a diesel truck. And there are plenty of dino-based HDEO's that show great UOA protection in that hot-oil environment.

I'm not that familiar with the workings of a diesel truck, so some of those details were hazy in my mind.

What struck me is that the Shell website did not seem to indicate the synthetic Rotella very strongly. By that I mean I expected to see them talk about its use in the desert southwest / Texas corridor, but they seemed to focus far more on the cold flow properties and its use up in the north during winter. That made me think that perhaps the conventional Rotella was probably perfectly okay for normal operations in desert conditions.

The website also mentioned the big "truck train" things operating in the Australian Outback as a test of the Rotella oil ... and they did *not* emphasize the use of synthetic.

Originally Posted By: dnewton3
Synthetics do handle extreme temps better; this is true. But by extreme, I mean E X T R E M E. Like -20 degF for cold starts, or "Oops - Honey, the temp gage is in the red and steam is coming from under the hood". Normal operating temps, around 190-210 degF, are perfectly acceptable for conventional oil.

I tried to pin the "Ask the Expert" folks at Shell what they meant by "extreme." There mentioned some rate of oil oxidation per degrees over 250 or something along those lines ... but that didn't help me because I don't have an oil temp indicator. Still, I had to believe my GL1800 riding -- tame, to say the least -- didn't qualify as "extreme."

 

[dnewton3]

Let me give you a couple of examples where "synthetic" oil saved the day, but isn't necessary in daily operation.

My Taurus: long story short here. (I have posted the whole drawn out story in the Oil Additive section, if you care to read it). The car was running conventional oil, and was loaned to a neighbor. Freeze plug burst open, car overheated, neighbor continued to drive the last few miles home (all stop and go), rather than get stranded during rush hour on a busy street! Many, many months elasped, and then I checked compression. Down in 3 of the 6 cylinders; way down. Used ARX (currently in second application phase) and saw a major restoration of compression. THE CONVENTIONAL OIL HAD COKED UP THE RINGS, AND WAS NOT ALLOWING THE RINGS TO SEAL AGAINST THE CYLINDER PROPERLY.

My wife's minivan: similar long-story shortened. H20 pump went bad on her way home on a long drive. She kept driving anyway, until she pegged the temp needle. I trailered it home. Coolant leak from warped head; drat! I did the top end rebuild myself. The vehicle had always been run on whatever synthetic I could find on sale (no brand loyality, just group III). While it was apart, I was amazed to see the faint cross-hatch honing marks still in the cylinders! Put it all together and it ran fine (still drives it to this day). I did a compression check, and they all were within a few psi of each other, right at the top of the spec! THE HEAT TOLERANCE PROPERTIES OF THE SYNTHETIC HAD PROTECTED THE ENGINE FROM THE EXTREME ENVIRONMENT THAT THE OVERHEATING CREATED.

Now, the point I'm trying to make is that NORMAL operation of a liquid cooled engine in no way necessitates "synthetic" lubricants. But when things go awry, synthetics can protect to a higher level. If the neighbor had pulled over immediately when the steam started coming out from under the hood, rather than continue to drive, then the conventional oil would not have coked up the rings. We cannot blame the oil for a human mistake.

So, if you feel that you can control the operating environment and always maintain your engine in a good manner, then synthetics won't make any difference to you, except for more money gone from your wallet. You're certainly not in an area where cold starts are a major concern. And with a properly operating, liquid cooled engine, synthetics gain you nothing IF you don't significantly overheat the engine.

The main benefit of synthetic oil is extended drain intervals. If you're not into that, then synthetics are a waste of money. Temp extremes are RARE.

BTW - what do I run in my vehicles? I have learned my lessons. Any vehicle that has the opportunity to be loaned out, or driven by a "non-gear-head" person, get's group III synthetic from the "on sale" shelf. I get a small piece of mind that I've got that little extra buffer of lubricant protection. But in vehicles that I soley control (my Goldwing, my Kubota tractor, my Duramax truck, my 1966 convertible Mustang) my intent is to run any brand name, quality HDEO dino oil. I know that I won't mistreat the vehicle I'm driving, so the risk is much lower, and therefore the "need" for synthetic is non-existent.

MORAL OF THE STORIES: NORMAL OPERATION OF AN ENGINE IN NO WAY NECESSITATES SYNTHETIC FLUIDS. Your GL will likely outlast your desire to ride it, given a steady diet of HDEO, decent oil filters, and "normal" operation and maintenance.

 

[wileyE]

It's not so much that the oil oxidize at high temps, it's what happens afterward, that's where the additive package comes in and deals with high temp oxidation. On short OCI bike engines (vs. the big rigs) their's plenty of additive to save the day throughout it's life. If your comparing volatility, true less, but who ever runs their bike oil so long that it thickens? more typical is it shears thinner by oci time. So rottela's reply may be accurate, it may not be as important for our needs in bikes.