0w 20 oil pressure?

i was gonna highjack another thread but thought id start my own. Anyone running 0w 20 fully, or 5w 20 dino and what pressure you seeing in your xj during hot/cold idle, and a steady cruising speed, also any issues with this thinner than recommended oil? Cheers.

You're talking about lowering viscosity at N.O.T by 30% from the factory recommendations, while using a modern oil that is already substantially down on anti-wear additive packages that are beneficial to our flat-tappet engine design.

Bad idea.

I agree with X-defector. Most XJ 4.0's have over 100K on them and probably have some loose tolerances. If anything, I'd consider a slightly thicker oil. I'm running GTX 10w30, and will be going to Rotella 15w40 at my next oil change.

0W or 5W 20 in the summer can't be good. I run 5W somthing in the cold part of the winter here in Ohio but as soon as the temp goes up much at all im back to a 20W50.

In the early days of Mobil One 5-20 was about it - and the Caddy owners who ran it were subject to engine failure. 70's era engine tolerances wouldn't take the reduced viscosity in summer temps.

Adding 50* to the ambient temperatures will push internal oil temps to their 280* degradation threshold. Doing that to a 0 wt oil not recommended by the manufacturer is probably not the best choice.

you could probably get away with a lower 'winter' number like a 0w-30 but i would not lower the 'hot' weight (second number) below 30. If anything i'd up it to a 40 weight in the summer.