Originally Posted by wstar

It's not about thinning the oil, and water doesn't "somehow" enter the pan...

The air around you contains humidity (especially in the Houston area). When the hot engine cools off overnight, the humidity in the air condenses out on the metal surfaces inside your engine (just like the dew you see on your car windows if you park outside) and drips into the oil, adding a small amount of water to your oil every time.

You also get fuel and combustion byproducts into your oil as part of its normal operation, via blowby on the piston rings. When those mix with water in the oil, they create an acid, which in turn will eat away at oil seals and promote engine corrosion.

Getting your oil regularly hot enough to boil off the condensed water slows down that process a lot, vs never getting up to temp and letting the oil become rapidly acidic. Water boils at 212F, so generally my target for a safety margin would be to ensure you get a few minutes of 220F oil temps on the gauge to boil off condensation.



If that's as hot as you can get it (and we're still in pretty bad summer heat), it's not strictly necessary to run a cooler. Those temps are within range. If you fear you will get the temps even higher driving in some other way (running the car harder), then try it and find out. I think you'll be surprised by what factors stabilize the temps and how hard it is to reach 260 on the street.



Even if you were exclusively driving in a very hot climate, I would get the Mocal sandwich plate. As noted above, it doesn't make a ton of difference to highway oil temps. However, you shouldn't be pushing the engine on cold oil, and the plate will save you a few minutes of your 10-15 minute wait for the oil to come up to temp when you start in the morning.

Aside from the Mocal plate, you may also want to make some blockoff plates for the cooler to use during the winter on highway drives, so you're not making the whole drive at like 170F, which is just bad. Again, as said above, overcooling the oil is bad too.