5.7 Chevy Engine Questions

[CCI]

1994 Chevy 2500 with 202,785 miles.

What should the oil pressure be at operating temperature highway speeds?

What's a good oil to run in an engine of this type and age?

 

[joegreen]

I think it’s going to vary quite a bit depending on wear. 40-60psi would be fine. Pretty much any oil from a 30-50wt. Maybe tailor the weight to the oil pressure and application

 

[sdowney717]

It should definitely be around 40.
LOP at idle when hot also indicates issues, maybe with loose bearings, bearing wear.
Still it can run for years like that, until it doesn't.

 

[CCI]

Gauge says 30 psi at highway speeds, operating temperature. No idea if gauge is accurate.

Just bought it. It has a bit of a knock at cold startup that goes away quickly and it feels a little more like a 4.8 going up hills but it runs fairly well for its age.

I will try a 10w-40 and a new filter and see how it does.

Thank you all for the response.

 

[ripcord]

The startup knock is probably piston slap which is very common when a SBC (or most V8s) gets some miles on it. Not a huge deal. The pistons swell a bit as they warm up and the noise goes (mostly) away.

40 grade oil is a good choice.

 

[4wheeldog]

Gauge says 30 psi at highway speeds, operating temperature. No idea if gauge is accurate.

Just bought it. It has a bit of a knock at cold startup that goes away quickly and it feels a little more like a 4.8 going up hills but it runs fairly well for its age.

I will try a 10w-40 and a new filter and see how it does.

Thank you all for the response.

Noise on startup that goes away might be piston slap. Which is much better than a rod knock.

 

[wtd]

I believe the acceptable spec is 10 psi for every 1,000 rpms.

 

[JN94]

I've got a 1990 C1500 with the same engine and similar mileage , I run 15w40 in mine. Hot oil pressure on mine at idle is around 46 psi and around 70 psi at highway speed based on a mechanical gauge and not the 35 yr old factory gauge.

 

[Exhaustgases]

30 psi is fine.

 

[Lawnman23]

The startup knock is probably piston slap which is very common when a SBC (or most V8s) gets some miles on it.

Piston slap was more of an issue for the earlier Gen3 (4.8/5.3) engines, not so much for the outgoing Gen1's (5.0/5.7).

 

[LDM]

Piston slap was more of an issue for the earlier Gen3 (4.8/5.3) engines, not so much for the outgoing Gen1's (5.0/5.7).

Agreed. I have never seen or heard of piston slap on the SBC. LSx, definitely, especially the earlier ones like the LS1/LS6, and the 4.8/5.3/6.0 engines derived from the LS1.

 

[Yourhomiematt]

I have a SBC 350 with unknown miles. Installed a melling high volume pump. With 4qts 5w40 and 1qt 20w50 in see about 60psi cruising, and 25-30 hot idle at 90⁰ ambient.

 

[clinebarger]

Piston slap was more of an issue for the earlier Gen3 (4.8/5.3) engines, not so much for the outgoing Gen1's (5.0/5.7).

I replaced MANY Fleetwood Gen II LT1's for piston slap when I worked at a Cadillac, Fewer Gen 1 Vortec's in the Escalades....But those owners tended to be oblivious to it & the mechanical fan masked it to a certain degree.

At the time GM treated Cadillac warranty claims differently than other divisions, They rarely denied or kicked them back.

 

[Expendable]

I replaced MANY Fleetwood Gen II LT1's for piston slap when I worked at a Cadillac, Fewer Gen 1 Vortec's in the Escalades....But those owners tended to be oblivious to it & the mechanical fan masked it to a certain degree.

At the time GM treated Cadillac warranty claims differently than other divisions, They rarely denied or kicked them back.

That is interesting, I wonder if any other manufacturers do the same?