BAD-HABIT

Just wondering about what is a safe oil temperature to run with synthetic oil? I understand that anything over 240-260 is too hot with Dino oil but Mobil 1 states its safe up to 400.... Can you run more oil temp with synthetics or not? I have seen alot of threads on oil temps but not any answering this question I have had for a while.

BH

Kidnova

Good question. I've been told by two local marine engine guys, both have good reps with the go fasters, that 270*+ is ok with synthetic. And I have heard of Mobil's claim about 400* being safe with their synthetic.

Ok, so synthetic is good to 400*. i.e. it does not break down at that temp, still provides good cushion and lubrication. I'm not a mechanic, but, what about expansion of the block, pistons, ring gap clearence, valve train, etc.?? It seems that that much heat would have an effect on the components and clearences.

My gut feeling is try and keep oil temps 230 - 240 or less, even with synthetic. I've been fighting oil temps all summer. In fact I'm putting in a bigger oil cooler {no. 3 so far} this week end. Hope it does the job.

MACDAD260

I use Mobil 1 15w50 in a 502. Once warmed up and cruising the oil pressure is 50 to 55 lbs. If my oil temp gets to 235-240* and I bring the engine to a 700 rpm idle the oil pressure will drop to 10 lbs. If I bump the idle to 1000 rpms the pressure will be 35-40 lbs. If the oil temp is less than 235* the pressure at a 700 rpm idle is 35-40 lbs. This tells me that at 240* the viscosity of the oil starts to go away. I don't know how this affects the lubrication properties of the oil but, it can't be good.

FlyFast

Macdad

My boat used to do about the same thing with dino oil. I have full closed cooling and was running a 165 t-stat. I put a drilled 145 t-stat and I like my oil numbers.

I run 30 wt and have wondered if 40 weight would give me better oil presure?

Mbam

Sutphen, I feel your pain but that damage is not because of hot oil. Hot oil is a symptom of another problem, not the cause. With everything right 400 hours on a set of bearings at 1000 HP @6000 rpm is not a problem.

Mbam

It's not magic, but in back to back tests I found Mobil 1 dropped my oil temp 20 degrees. I was racing in the Bahamas back in 97, nice and calm, a full throttle race. 1100 HP blower motors (not mine). Lost oil pressure, I mean the big 0, I tapped the throttle man who was the owner on the shoulder, pointed at the gauge. He shrugged his shoulders and we kept going, another 1 1/2 laps (20-30 miles around Paradise Island) before the engine seized.

After the race found the oil pump was lying in the bottom of the pan. We were running Mobil 1, but of course i have not tried this with regular oil to see the differance

minxguy

Oil is rated for viscosity on the high end at 210 degrees F. Oil temps of 230-240 are not excessive. You should start looking for a way to cool you oil if you start seeing temps. nudging 300 F. I have personally seen oil temps in Legend cars ( they use a 1200cc yamaha motor) exceed 345 degrees, as a matter of fact the oil temp pinned the temp gauge. engine oil can stand running at elevated temps for a while but it's in everybodies best intrest to keep the temps at a manageable level. Synthetics can "live" longer at elevated temps than petroleum based products but try to keep temps in the 250-270 range and life will be good. You must also not over cool an oil. Min temps should be 180. If oil doesn't get warmer that this it is very diffiult to "cook" of condensation. Ken

Wobble

We run TUSA Modified Lite's. (dirt version of Legends Car with mods) This past year we switched to M-1 v-twin 20-50. At the first freshen up the builder called to see what oil we were running as he was amazed at the lack of wear. (we had been running M-1 15w50 previously)

It is not unusual for us to see 320* oil temp on a "tight" track

This oil seems to be in a league of it's own.

I run it in almost everything I own.

Hydrocruiser

...mechanic called to see you use M-1 V-twin...bearings looked that good??..really>>?....V-twin isn't only for motorcycles you silly wabbit...

No oil should be allowed to run outside of normal temp ranges by the way...got that?

Wobble

Not recommending 320* by any means, but in dirt racing track conditions have a major effect on engine load. A dry slick track may only cause engine oil temps of 270*, but a tight tarck where you stay hard on the throttle most all of the time causes a lot more heat build up.

You are not going to back off because something is getting hot. Instead you use products that can take the abuse.

Thanks to your research Hydrocruiser. We decided to try v-twin oil and will probably not change unless mobil ups their game even further