+1 the best oil cooler you have is the finned sump. I'd take that off first and see if that makes a difference.

By the way a 13 row oil cooler will drop oil temp by approx 20°C, but you really need to find out if oil temp is your problem.

I've previously posted that i ran my car at wakfield park with a 13 row oil cooler and with the air flow blocked off (piece of carboard). Ran car for 6 hard laps and temperatures recorded at cooler outlet were
96°C without oil cooling
76°C with oil cooling
tests run on the same day, ambient air temp approx 16°C
Oh and by the way, during both test sessions water temp on the gauge was the same

On the highway the other day in my 1406cc the oil got up to 105 degrees. Wish I had an oil cooler then. So I'd be putting a gauge on to monitor the temp then see if you need it. Around town it's never gotten over 80 degrees. So next time I do an extended highway drive ill probably throw it on.

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If you do intend to monitor your oil temperature make sure you look at it on cold days as well as hot days.
The oil temp on very cold days is sometimes almost too cold even without a cooler.

It is possible to run a thermostat on an oil cooler. It might be the smartest option

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i like it loud

I don't run an oil cooler. The temperatures where I live run from minus 10° in winter to 44° in summer.
Using an oil temp gauge in the sump and I have not seen the need for an oil cooler with any of my road car motors over the years.
I did run an oil cooler on one car years ago but that was back when I was young and knew everything.

When I was using MR BN (fast road / track car) as a daily driver I put a bit of plastic over the oil cooler in winter.

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Too many cars, and too little time.

So, what is considered to be the optimum working temperature of the engine oil?
What would be the upper and lower temperature levels were the oil will still lubricate at a sufficient level as not to cause damage to the engine?
What temperature would warrant an oil cooler to be fitted?

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WD40'll fix it!
If it don't, use a big hammer!

Quick , easy , cheap fix , top idea , food for thought

Your car doesn't care about oil temp, but the oil does. Your car does care about oil pressure although "how much" is a topic for many beers. One old reference point was 10 psi/thousand revs. Once warm mine runs 75psi (because that's what I adjusted it to) over about 3000 revs. Part of me says I should adjust it down but it makes me feel comfortable.

Pressure drops as temps rise (and with age) - but if age is the problem then the pressures won't recover.

So if your oil is thinning you pretty much have two choices. Reduce the oil temp (get a cooler) or buy better oil (some (synthetics especially)) don't really mind getting hot. You don't really care how hot just accept that hot enough to (significantly) drop the pressure is too hot (for the oil you're using).

Modern multi grade oils have chemicals to stabilise oil viscosity and some do it better than others.

If you are using a "solid" sump guard then removing it would be step one. If this doesn't work then try the cooler - or maybe buy better oil - then try the cooler.

More beer needed.

Cheers, Ian

Alright so I'm fitting an oil thermostat so that the oil loop can bypass the cooler if the oil isn't hot enough. The only problem is that I have been told many different things about my oil temperature. It seems to drop pressure once it gets over 210-220F so should I get a 180F 200F or 220F thermostat, I'm leaning towards the 200F one. But I'm no expert so...

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i like it loud

What brand oil are you using? Some brands will drop pressure down to 50's and others won't thin out at temp. Try Castrol Edge 25W50 and see if you get the same problem.

40's isn't that bad IMO. Provided it's back up at speed, that's all that matters.

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Lillee - 1969 Morris Mini K

thought id update you all, installed a 13 row oil cooler, oil pressure remains at 75psi all day long till i go below 2500rpm but never drops below 60psi even at idle

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i like it loud