Oil temperature

listernoble · 25 Mar 2005, 18:25 (Ref:1261663)

What is an approx max temp for race quality synthetic engine oil?
I've been told max 120 deg C but I'm sure it can run hotter than that as synthetics were designed for jet turbine lubrication.
Lister

**dtype38** · 25 Mar 2005, 19:01 (Ref:1261696)

Mate with a Lister Jaguar running on Castrol RS used to run his up to 130C without troubling the oil. Engine wasn't overly keen about it though.

**Peter Mallett** · 25 Mar 2005, 21:22 (Ref:1261800)

I run mine at 100. If it goes above 120 I'm looking at stopping. That's with Castrol RS or Millers 20/50, the same rules apply either way.

**Tim Falce** · 25 Mar 2005, 21:30 (Ref:1261803)

Why have an oil temp gauge, it's just more stuff to worry about

**Peter Mallett** · 25 Mar 2005, 21:43 (Ref:1261903)

There's a word here but I'm struggling to find it. I think it starts with "a" and ends with "e" but ...............................................

**Tim Falce** · 25 Mar 2005, 21:54 (Ref:1261914)

Sorry, it was meant to be a serious statement.

**GTRMagic** · 25 Mar 2005, 23:14 (Ref:1261971)

Quote:

Originally Posted by falcemob

Why have an oil temp gauge, it's just more stuff to worry about

It should be a warning light, or alarm system if you have digital dash/ datalogging... I am not sure how many pilots look at the oil temp gauge, when the oil pressure is more immediately valuable to understanding whether she is gunna blow captain...

**dtype38** · 25 Mar 2005, 23:24 (Ref:1261979)

Quote:

Originally Posted by Peter Mallett

There's a word here but I'm struggling to find it. I think it starts with "a" and ends with "e" but ...............................................

That would be two words Peter

gttouring · 26 Mar 2005, 03:07 (Ref:1262059)

yup run oil temps at 100- this keeps the water out nothing condensed in the oil it all steams out...
funny how many people in the states can't figure this out and run or say 185 F, sounds good... bah the fools
(not talking about Oil cooled Porkas though)

halecmini · 27 Mar 2005, 19:56 (Ref:1263076)

they can go upto at least 140.. but every one is differnt, if you look on the can it will have a code on it, this is an american coding two letters (A is the first) i think the best spec is AJ and worst is AA!!! take a look in the motorcycle (R1) haynes manual it tells you in there!

Al Weyman · 27 Mar 2005, 20:47 (Ref:1263130)

Hot oil temperature (within limits) cool water temperature is reconned the way to make power. I have just fitted an oiil temp guage in my historic Camaro today by coincidence. I have fitted the sender into the sump, some say it should be measured post cooler others say at the sump but as the sump had a facility thats where it went.

**dtype38** · 27 Mar 2005, 21:49 (Ref:1263181)

Al, could you expand on why "hot oil, cool water" gives more power. Oh, and I think you have your oil sensor in the right place. Putting it post cooler only tells you how effective your cooler is, not how hot the engine is getting!

Al Weyman · 27 Mar 2005, 22:26 (Ref:1263200)

It's only what have read in Yankee articles, I guess the therory is that the hotter the oil (within reason) the thinner it gets so less crankshaft windage and the cooler the engine runs and by this I mean getting to optimium operating temprature then every thing is at the right tolerances and also the temp of incoming charge of air is also kept down. I will try to dig the article out tomorrow it may relate more to big V8's which on the road traditionally run at higher tempratures with a lot of under bonet heat.

Chucky · 27 Mar 2005, 23:04 (Ref:1263227)

Hot oil, cool (sometimes cold!) water is the way to go.

Hot oil (approx 110-120C) is where modern synthetics want to operate. The additives all work properly at those temps. Some synthetics anti wear additives are barely functional at 185F! And a good point by gttouring, over 100C keeps the condensation out.

Cool water is mostly there to keep cylinder head temps down. It adds in detonation resistance. A lot of people point to F1 and claim that they run ridiculously high coolant temp. This is true but only because they run such tiny cooling systems for weight and aero reasons.

Al Weyman · 27 Mar 2005, 23:10 (Ref:1263230)

Yes the pre-detonaton problem, that was the other reason thanks for that Chunky, even if your road car gets hot you can hear it tinkling away.

greenamex2 · 29 Mar 2005, 10:07 (Ref:1264113)

Having spent Monday (and most of the last 5-6 years) driving round watching my oil pressure and temperature readings I offer the following observations -

Thicker oil = higher oil pressures BUT also higher temperatures. It is also very possible to end with LOWER pressures because oil gets so hot it both thins out and breaks down.

You do NOT need your oil at above 100 degrees C. Water only boils at 100 degrees (ish), it quite happily evaporates at anything above about 0.2 degrees C. By the time you get into the 80's you aren't going to have much water left in the oil.

Bigger oil coolers aren't necessarily better. Often the problem is air flow in AND out.

A surprising amount of heat can be generated by the crank hitting the oil in your sump. I effectively dropped the whole sump a couple of inches and lost about 20 degrees in oil temperature.

As regards the original question, depends on the type of oil and what your oil system is designed to cope with. If you run a proper race synthetic single grade oil then the oil will cope with 120-130 degrees plus and still recover. However the massive difference in viscosity between cold and hot means your oil pump must have a large capacity AND a very effective pressure relief valve. A normal multigrade road synthetic will have it's numerous extra components break down at these sorts of temperatures and you will have to replace it often.

The moment you suddenly realise that your oil problem is just down to a combination of enlarged clearances and insufficient oil pump capacity is a very happy one!

Out of interest I am working on a range of relatively cheap LCD based temperature/pressure guages with an LED warning light. If someone thinks there might be a market for a really cheap warning light only based system then let me know.

listernoble · 29 Mar 2005, 11:59 (Ref:1264198)

Thank you for all the replies,the car in question,a friend's Ginetta G4, ran almost non stop for approx an hour at Castle Combe yesterday,with an indicated oil temp around 115 deg C and no problems.
He runs Morris Competition 10/50 synthetic so the oil should be OK for a few more events or would you change it?
Lister

zefarelly · 29 Mar 2005, 12:20 (Ref:1264223)

I havent got an oil temp gauge, thus far if the water temp ever goes up then the oil pressure goes down as it too gets hotter

my new ally rad has brought that down to around 75 degrees C which is nice, oil pressure has been around 60 PSI, which is also very nice ! we'll wait until the summer and see how it behaves then.

**Peter Mallett** · 29 Mar 2005, 15:17 (Ref:1264354)

Slightly off topic. We fitted an electric water pump this year. I'm now able to sit with the engine ticking over for a few minutes. Previously the temps would climb pretty fast and I'd have to switch off. Mind you I did that after practice was red flagged and needed a push!

The point being that my oil temps never got above 90 degs.

Al Weyman · 29 Mar 2005, 18:40 (Ref:1264518)

Is that electric pump or fan Peter, reason I ask is the ones I have seen for sale for Chevys were strictly a Drag Racing piece. I remember many many years ago when I was a spanner man at Nathan Racing we tried an electric pump on the Imps but it was not overly successful.

**Peter Mallett** · 30 Mar 2005, 07:40 (Ref:1264981)

Its an electric water pump. I don't run a fan.

zefarelly · 30 Mar 2005, 10:28 (Ref:1265101)

yes you Do Peter . . . .Pat comes along to all your races

I've seen a good few of the hot rod anglias running electric waterpumps, I thought about a small auxilliary one to keep circulation after switching off to stop the head overheating, but my new Ally rad seems to have cured the problem anyway

**dtype38** · 31 Mar 2005, 07:59 (Ref:1265985)

Water circulation doesn't stop just because you turn the engine off. The hot engine still causes it to rise and the finned radiator still lets it cool down causing it to fall. At least until it cools down enough for the water thermostat to close (if you have one).

**Peter Mallett** · 31 Mar 2005, 09:15 (Ref:1266044)

Don't run a thermostat either.

Agreed that circulating the water for a while after stopping is a good thing.

Zef. Who made your rad?

zefarelly · 31 Mar 2005, 10:40 (Ref:1266069)

Pete . . .I'll PM you, its a Throbnozzle racing special !

what I used to do was leave the car 5 mins then turn it over quickly to just circulate, its not a problem at the moment and with no stat the waters free to move anyway

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