Robbie Boyd

On Start up, it's a little over 40psi on the gauge. After running for a while, it drops down at idle (around 20psi) and after like 20 minutes it drops again (around 6-7psi?), but will rise back up again when I hit the gas. During highway cruising and under load, it's fine too. I was thinking that with a higher mileage car like mine, maybe I should try another kind of oil. Currently it's 5w-30, but I wondered whether switching to a thicker oil or trying Mobil 1 synthetic 0w-40 would work.

I've had a trusted mechanic look at it, and he tried changing the sender but it didn't do anything. He said it's not the pump, and that the engine is getting oil (I'm assuming he used a mechanical unit to check oil pressure). I've read in a book that for an engine idling at 800rpms it should have atleast 8psi of oil pressure.

I'm really hoping it's not a bad bearing. Everything else engine-wise is running surprisingly good. Last week I got 320 miles on 1 tank of gas! (all highway).

Suggestions?

brandboZ28

iTrader: (2)

LT1's are somewhat notorious for having low oil pressure but like you said, put a little thicker oil in it and your pressure should jump back up.

Just saw your sig. 137k is fairly high mileage for 5w-30. A thicker oil should "fix your problem".

buffman

iTrader: (9)

Mine reads on the low side on my 150k LT1 but I'm unsure of the accuracy of the electric autometer gauge and whether or not that spot above the oil filter in the block is a good place to put the sending unit?

slowmofo

iTrader: (6)

thats normal, I installed a larger oil pump and pressure is up alittle higher then it was with the stocker. My car scared the crap out of me when I first got it because I always though the pressure was low, but It was stock for 4+ years like that and was perfectly fine.

DarkDemon

iTrader: (7)

mine is like 25 or so at idle and usually at 40 or higher the more gas i give it. scared me the first time i idled when i saw the pressure drop from 40 to 25

dhdenney

iTrader: (53)

I'm using Mobil 1 15w-50 and mine rarely gets below 45 at idle. Driving is like 60.

M29_Formula

I've got 101k on my 93 and I run Mobil 1 10W-30. Pressure looks about like so...

Cold idle: 45
Hot idle: 30
Cold driving: 50-70
Hot driving: 45-60

I have noticed though that the pressure drops slightly from about 60psi to ~45psi at the top of 1st when I romp through the gears. Doesn't do it in any other gears though.

buffman

iTrader: (9)

I'm running Mobil 1 0w40. I myself question the accuracy of my gauge. I think after full warming up and oil temps are in the 200 degree range (taken from autometer sending unit in oil filter adapter) Pressure is like 12.5 psi @1000rpms. I want to pick up a cheap mechanical guage and see how accurate/inaccurate the gauge is. Not sure I can really compare it to your guy's F-bodies unless all LT1s used the same oil pump??

Matt

Robbie Boyd

I'm now between getting Mobil 1 10w or 15w. Glad (I guess) to hear it's a fairly common problem.

Robbie Boyd

So I just put in some Castrol High Mileage 10w-30, and the pressure still is kind of low. Not zero (yet), but I was hoping for a little more. The car drove fine though.

I'm praying it's not a serious problem, although I did notice that my oil pan looks a bit dented, (speed bump?) maybe affecting the oil sump?

whatbrown

I have a 96 ws6 with even lower oil psi. cold it's about 45 at idle and close to the same while driving. The idle pressure drops fairly quickly as temperature rises- all the way down to 0 at idle when fully warmed. driving while fully warmed is between 20-30 max. i had sending unit changed as well. now, i will use some seafoam in the crankcase and get an oil change with 10-30 and a good filter like k and n. car runs beautifully and makes no noises.