All the searches I conducted I'm starting to think I'm going to need a new engine, no biggie in the up coming months... However I have a question


Background:
305 V8 5.0L
10w30 Syn Oil (Mobile one)
Micronic Filter (Purolator)
Lucaus Olis Stabilizer (Syn type)

Issue:
Car starts cold at 35 psi
after warm up (10 mins) its ranges from 15 idle 28 crusing
Now after 30 minutes or so driving,
In park it stayes 10 psi constant
In Idle with my foot on the brake it drops to 5-7 psi (best guess)

I plan on putting a mechanical gauge on it this weekend. If these readings are accurate is this a problem? Or normal?
Thanks in advance

 

hey pal, dont mean to hijack your thread or anything, but ive got similar problems. was told the sender unit is probably on the fritz, but no way to know without testing with the gauge as you mentioned. Does your gauge drop down to deep in the red when stopping, or is it constant? Just wondering. If you don't mind, please let me know what type of gauge you got, where and how much.. I'll be doing the same thing.. thanks

 

ive been told 10 psi at an idle was ok...personaly it think its kinda low...i like to see at least 20...if you have high milage multi grade may not be the best oil to use but thats just my opinion...hopfuly somone with more knowledge will let us all know...good luck tao

 

That is always Step #1 when diagnosing a low oil pressure issue.

 

would still think a multigrade would be best being that without it your oil viscosity will be all over the place.
when cold could be too thick which will cause wear or too thin when hot which could cause wear

 

btw where at in idaho are you?

 

The whole mechanical gauge thing, while very good technically, is a whole bunch of extra fooling around and expense, that you don't need to hassle with.

Instead, just go buy a new oil pressure sending unit, and replace it. The gauge itself almost never goes bad; but the SUs fail often.

If that doesn't fix it, then it's time to start saving for a rebuild. Or, if you just want to be double-sure it's not the gauge, do the mechanical thing. But I'd bet a paycheck (yours, not mine ) that it won't tell you anything different.

If it DOES fix it, then lose the Lucas, and keep using the oil you're using; which is just fine exactly as it comes out of the bottle.

 

Dont worry about 10psi in park, Chevys only need 10 psi/1000rpm. Once my coolant temps hi 200+ my psi at idle (in D) can read as low as 10-13, no worries.
Last motor I built had a Melling HV55 pump. Idle @15 lbs, warm on a fresh motor.

 

This is going to sound elementary, and I don't mean to insult your intellegence, but did you check the dipstick and make sure you don't need to add any oil? Low oil level = low oil pressure. (duh)

Trust me, I've seen some people do some stupid things, so thought it could be possible.

Good Luck

_Clark

 

i check mine on a regular basis, and it actually reads well above the "operating" level.. I'm not sure if thats normal or if my bearings are going bad... I put the 5 quarts recommended every oil change. When I got the car, I was told it was a 350, would I be overfilling then, as I have come to understand that 350s require less oil? When I get a day off it'll be one of the first things I check.

Jamessr, again, sorry for hijacking your thread.

 

I have had the very same issue with my 305 and replaced the oil pressure sender and it made no difference. When I always would drain and change the standard 10W30 it came out like water. Have been running straight 30W and it put me right back where I need to be with the pressure I need.

A compression tester is the proper way to figure out the issue. High mileage engines are bound to loose compression at sometime. My LO3 has about 150k on the clock, but still runs and sounds great other than that.

 

rx7 makes a good argument for muli grade...one ive heard before and starting to wonder about...i still run striaght 30 with no problems that i know of...temps here in boise are the same as caldwell(pretty cold right now lol) tao

 

 

Can you explain this a little more? I've never used a compression tester to diag low oil pressure.