I did some searching, but I didn't find the exact answer I was looking for...

About a month ago I decided to go all out with my GTO so I picked up a 1999 Silverado with the 5.3 (no mods) with 70K on the clock as a tow vehicle. I initially didn't notice anything out of the ordinary, but I started to notice the oil pressure was a little lower than I have seen in friends Silverados. So I guess the question is... What are you fellow Silverado owners seeing for oil pressure during different driving conditions? I see 40 to 45 PSI on start up and as low as 25 to 30 PSI when the oil is nice and hot. I know the rule of thumb is 10 PSI per 1K RPM, so I am still way safe, but I thought I would ask the board to gain some piece of mind.

Thanks

Chris

 

what oil do you use and have you changed it since you purchased the truck?

 

5W-30 Castrol GTX and yes I have changed it since I bought the truck... 6 quarts and a new AC Delco Filter.



I guess I will ask 1 other question while I have your attention on this subject... Does anyone make an oil additive that "Rejuvinates Seals"? I know the pump is working well since it jumps up really quick with a little throttle, but I suspect it is loosing some pressure due to the mileage on the seals. Please advise...

Thanks again,

Chris

 

throw in some 10-30 and a bottle of lucas.

 

yea up the viscosity some! might help a little

Lucas for the additive as stated above

 

On my 5.3 at idle i would sit at about 30psi sometimes a **** hair lower.
I could nail it and it would rise with rpms up to 80psi.
I always ran syn.5-30

 

I have 50k on the clock, and mine is between 40 to 45 psi at idle when warm, using 10w-30 Mobil1. Cold start up, it's usually around 60, and WOT the needle just about pins itself to the right. I'm sure that the factory guage isn't the most accurate, but these numbers seem pretty consistant with what I've read here and on a few other forums. (with Mobil1 5w-30, the warm idle psi was closer to 40 psi than 45, but with 10w-30 it's closer to 45)

 

Ok well that seems fair... I figured uping the weight on the oil would give me a little more pressure at temp! I just wanted to make sure the motor wasn't doing something abnormal seeing as how 70K is not a lot of miles on a motor these days!

Just for my info.... the jug of Lucas takes place of one of the quarts of oil during the change... not in addition to it; right? 6 quarts total...

Thanks for all your help,

Chris

 

Yessir (When I change my oil, it usually comes out to be a little over 6 qts...between 6 1/3 to 6 1/2, but I'm using PF59 oil filters which have been discontinued and may be a little longer than some of the other popular filters...I bought a bunch of em when I found out they stopped making them <I think I'm down to my last one as a matter of fact>)

 

i use 5-30 Mobil 1 5 quarts and a quart of Lucas Oil Stabilizer. I Haven't seen a pressure change yet but within some miles after the oil viscosity breaks down and pressure doesn't drop significantly.. If you think Oil pressure is low use and external oil pressure gauge like an auto meter or something equivilant to it and watch it. I've seen too many stock gauges read lower than it really is