I recently changed my oil. I was running Royal Purple 5W-30 synthetic and at hot idle I would run 40 psi. Yet now that I changed to German Castrol 0W-30 syntec I know see 25-32 psi at hot idle. Is it bad that I dropped this much pressure??? And what exaclty does lower psi mean, flowing slower, lubricating the engine less??? Im in Houston, seeing 95-100* heat. I have a 160* therm and dont see above 190* coolant temps.

Edited to Royal Purple, I wasnt thinking right when I posted and stated I was using Mobil 1.

 

Probably fine. With 0W, I guess you could expect a little lower pressure. That's pretty thin.JMHO

 

Once up to temp the M1 was a lot thinner than the 0w30, M1 runs near 20wt. and the Castrol near 40wt.. The 0w30 is a better choice for this motor, I do find it odd that your pressure dropped though.

 

Anybody else? And I dont believe 0W-30 is too thin for Houson temps. I have seen many people recommend it, including Patman. Any advice/ ideas appretiated.

 

I'm not a big fan of the O-W on these motors, They weren't designed for it. I would stick with a 10-30W Synthetic . Just My .02

 

25-32 at hot idle, that is more then enough. I wouldnt worry about anything unless you drop below 10psi hot.