K24?
I'd still like to know what synthetic oils these days are good to before they start breaking down from heat.
I'd still like to know what synthetic oils these days are good to before they start breaking down from heat.
What is the upper limit for oil temps?
- Thread starter vinu_neuro
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Dodge Neon SRT4
Think time-at-temp. That's what that old ATF chart was all about, oxidation rates. The oil oxidizes as surely at 210 as it does at 260, but it happen more slowly. Some oils may oxidize more quickly than others and that is a product of both the base oil and the additive pack. They ALL break down with heat, some can just stand it longer or don't oxidize as much at the higher temps. Flash point would be a good, often seen, indicator, I'd think.
Rather than thinking in terms of finding an oil that can withstand heat, perhaps the best long term solution is to find a way to keep the oil temp lower and at a stable temperature. The more I think about that, the more it looks like an oil-to-water oil cooler is the way to go. It warms the oil quickly for good flow and to bake out moisture, then it stabilizes the oil temp to somewhere near coolant temp (actually lower on the one engine in which I've see tests, but I don't know if that is universal). An oil-to-water cooler with a thermostatically controlled oil-to-air cooler to control temp spikes would be the ideal for a working rig.
Rather than thinking in terms of finding an oil that can withstand heat, perhaps the best long term solution is to find a way to keep the oil temp lower and at a stable temperature. The more I think about that, the more it looks like an oil-to-water oil cooler is the way to go. It warms the oil quickly for good flow and to bake out moisture, then it stabilizes the oil temp to somewhere near coolant temp (actually lower on the one engine in which I've see tests, but I don't know if that is universal). An oil-to-water cooler with a thermostatically controlled oil-to-air cooler to control temp spikes would be the ideal for a working rig.
dino 250F
Syn 300F
I track my S4 and see oil temps around 280F, oil is GC..
after that event I ran oil for another 5K and UOA came back with same wear rates when I didn't track the car...
Syn 300F
I track my S4 and see oil temps around 280F, oil is GC..
after that event I ran oil for another 5K and UOA came back with same wear rates when I didn't track the car...
one of the guys in the miata group was regularly seeing 270F on his FI mazdaspeed miata in the AZ heat. at that point he was using M1 0w40, but when he switched to 0w30, the temps came down to 230-250 under approximately the same conditions. he tracked once with the 0w30, but i recommended he go back to the 0w40 and add an oil cooler which he since has done.
the point here is that thicker isn't always better under high heat. which one will do better, 0w40 at 270, or 0w30 at 240? certainly going to 20w50 would have been counterproductive....
the point here is that thicker isn't always better under high heat. which one will do better, 0w40 at 270, or 0w30 at 240? certainly going to 20w50 would have been counterproductive....
hehe they would do the same 0-40 at 270F is same viscosity as 0-30 at 240F
Originally Posted By: zoomzoom
hehe they would do the same 0-40 at 270F is same viscosity as 0-30 at 240F
yes, and i would imagine that 20w50 would heat up until it hit the same vis. however, the decremental effects of the higher heat on the base oil, additive package, and the engine components would not be, i believe, inconsequential.
you make a very good point here though.
hehe they would do the same 0-40 at 270F is same viscosity as 0-30 at 240F
yes, and i would imagine that 20w50 would heat up until it hit the same vis. however, the decremental effects of the higher heat on the base oil, additive package, and the engine components would not be, i believe, inconsequential.
you make a very good point here though.
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I think oxidation rate is proportional with oil temperature, the hotter the oil the faster it oxidizes.
so in this case running 0w-30 at 240F is better all other things being equal.
so in this case running 0w-30 at 240F is better all other things being equal.
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actually, on the calc i just did, the 0w30 would be slightly thicker at 8.12 vs 7.77 for the 0w40, but it is a small difference. for 20w50 (assuming that 8cSt is where the engine will level out at) you get 284F. OUCH
Originally Posted By: vinu_neuro
At what point is oil temp considered too high? Do you really need an oil cooler past that point, or can you just go to the next higher viscosity? Track application.
i've heard a thousand times that for track duty, most cars will benefit from 1 step up in visc and an oil cooler. i'd also want an oil temp gauge and a working low oil pressure/oil level idiot light. a big red one
forgot to credit that Amsoil site i found the NOACK info on, http://www.1st-in-synthetics.com/what_is_the_noack_volatility_test.htm
At what point is oil temp considered too high? Do you really need an oil cooler past that point, or can you just go to the next higher viscosity? Track application.
i've heard a thousand times that for track duty, most cars will benefit from 1 step up in visc and an oil cooler. i'd also want an oil temp gauge and a working low oil pressure/oil level idiot light. a big red one
forgot to credit that Amsoil site i found the NOACK info on, http://www.1st-in-synthetics.com/what_is_the_noack_volatility_test.htm
The Sequence IIIG engine-dynamometer lubricant qualification test operates at 302degF oil temp and 239degF coolant temp for 100 hours of operation.
So the oils are tested up to 302degF.
Some engine designs can't tolerate that high of sump temperature, before main bearing bores distort which leads to higher oil temperatures.
So the oils are tested up to 302degF.
Some engine designs can't tolerate that high of sump temperature, before main bearing bores distort which leads to higher oil temperatures.
wow that's impressive and from the oil specs, dinos only lose 12-13% typically to volatization, syn 6-10%
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