Losing Oil Pressure?

[PlayingWithTBI]

I bought an 04 Chrysler Crossfire when they 1st came out (same chassis and drive train as the Mercedes SLK320). They required Mobil1 0w-40 (European spec) out of the factory. When I bought my 88 C1500 5.7L in 02 the PO had just put in a MR Goodwrench long block and used Mobil1 10w-40. For convenience I switched it to 0w-40 until around 08 when Chrysler changed their specs and said 10w-40 was OK so, I went with that in all my cars including our 02 Infinity Q45 4.5L V8 and our 03 Durango 4.7L. I'm still running with the same small block from MR Goodwrench 17 years later and it doesn't burn/leak any oil between changes usually at around 5000 miles.

 

[OBS_Build]

20psi at hot idle and 40psi moving sounds fine for a 5.7L to me. I would be curious what your pressure is with 5W-30 though, that's what the manual calls for.

Personally I'd be more worried about the EGR and the catalytic converter if I were you.

I'll probably end up cleaning the EGR pretty soon, and the cat is something I'm probably not gonna need because I plan on cutting my exhaust off right after the cat then hollowing them out, or getting an actual exhaust I really haven't decided

 

[DerekTheGreat]

I run 5W-40 Valvoline SynPower in our trucks. Change it every 5k in unison with Wix XP filters. My engine has 155k on it and burns a qt of oil every 4k miles, which in my mind says it doesn't burn any. The 302 in my Town Car gets the same oil as well, we actually run that in any engine first engineered in the 50's & 60's. But that thing burns about a qt of oil every 1k miles. I used to run 5W-30 SynPower in that engine, switching to 5W-40 hasn't negatively impacted anything in any of our vehicles. The only way I'd run what the oil cap suggested is if I got it with 100k miles on it or less.

Keep in mind that the "W" is simply cold weather performance, Winter. The number before it, 5, 10 or 15 indicates what viscosity that oil will behave like at 32F or so. So if it says "5," that means your oil will be roughly as viscous as a straight 5 weight oil at that temperature and so on. Make no mistake about it, all of those oils will be much more viscous when cold. The lower the number though, the better the oil will flow when cold, especially synthetic oils. The last number is the oil's viscosity when hot. Hot is some specified temperature just like with the "W" rating. From all the stuff I've read, a 5W-30 will be the same viscosity when hot as a 10W-30. So if you're looking for a thicker oil when hot, the final number is what you're after.

Lastly, your sending unit could be dickered. They fail after awhile and the replacements (even A/C Delco units) aren't all that great. I went through three on my truck before I finally got one which didn't leak or not allow the sender to return to 0. (that is important to me as I'm much more likely to notice the "Check Gages" light). Both OEM units on our '88 454 truck and our '89 350 truck failed in a way where they indicated 0 psi when hot.

 

[454cid]

I think the manual for my 98 recommends 10W40 as one of the summer options?

Acceptable is not the same as a recommendation.

 

[fancyTBI]

I run 10w30 in the summer and 5w30 in the winter. Had 323k on my 4.3. Didn’t burn any oil, no smoke, no nothing. Been in the family since 98 and this was a 92 truck. I know it isn’t Vortec.

 

[Supercharged111]

Acceptable is not the same as a recommendation.

Go on.