I live in WI so it gets hot in the summer and freezing cold in the winter. Can I run 10W x 30 all year round? I will be installing a frost plug heater before next winter so it should keep the thicker oil flowing. It seems the 10w x 30 keeps my oil pressure higher in the heat. I hate seeing it drop down to 5 psi at idle.

Any thoughts?

RIZ

If your oil pressure really drops to 5 psi at idle, by all means run the 10w30. Just remember multi-grade oils are supposed to maintain their 30 weight designation when hot but flow like the lower number when cold. I put 10w30 in my 4.0 but didn't like the slower cranking speed when it got REALLY cold. My hot oil pressure didn't change with either.

I'm using Valvoline 5w30 Max Synthetic right now. She has 158K on her.

5-30 year around.

Rebuild or get used to it. Raising oil pressure with heavy oil is ridiculous and will not offer any benefit. FYI mine has been running 4psi for years and thousands of miles, so don't panic. Low pressure is a condition of wear. Oil pressure is not a dynamic function....oil is still flowing through out the engine. Raising pressure with heavy oil will make it flow LESS!!

My 4.0L XJ loved Rotella T6 5w40, smoother and less noise. The first two oil changes(4500mi interval) using it my oil was incredibly filthy, even though I use synthetic, after that it was almost the same color when I changed it. I used it in my 99 4.0 WJ and currently use it in my 4.7L WJ.

Also this is an interesting read!

i run 5w30 dino oil year round, change it once a year

100f in summer, -40 in winter