Johnnystock

iTrader: (6)

**EDIT; PROBLEM WAS THE GAUGE. PUT BACK THE STOCK UNIT AND OIL PRESSURE IS ALWAYS 42PSI+ **

Car Has a LS3 cam and hi press Melling pump installed since march. Everything was fine and I switched oil recently from 5w30 Castrol synthec to Amsoil Zrod 10w30.

I went for a road trip 400miles and some 50-75 miles in town and noticed the oil press fell in the 26-29 psi range for the 1st time. It was randomly changing on the highway in 5th 6th gear. I put it in neutral and revving it did not raise the pressire oil temp was 201-209. Hot outside but nothing bad.

Comes to a light at idle and car hits 38-41 psi. I accelerate to 2k rpm and it falls to 28-31 psi.

No leak so far except the oil cooler, but its been like that for a long time.

Im really worried now to go back and drive 400miles again. Should I flush the oil back to a 5w30?

I will check quickly for a loose timing cover bolt. Cant check the pan bolts I need a lift or something.

Aerated oil maybe?

Car has an aftermarket oil sensor. Going bad maybe?

I made sure the oil pump oring was not pinched. Cracked pickup tube?

C6smackdown

iTrader: (1)

Seldom will oil pressure rise on free revving. If it does, it won't rise in the traditional manner since there is no load on the engine. If the OPS fails they usually max out. Why did you change viscosity? It sounds like your engine is too tight for that viscosity. That being said, 28-31 psi at 2k is perfectly fine.

**correction** I just actually read your post (I skimmed before) and noticed the both oils are 30 weight. The change in oils wouldn't have any ill effects at operating temp. My bad.

Johnnystock

iTrader: (6)

Thanks I appreciate the comments. Im really worried because I did the cam swap myself. I will switch back to 5w30 as a start.

Johnnystock

iTrader: (6)

Little update* I added oil and I gained pressure a bit but Im overfilled by 3-400ml. Its weird the car idles at 38-41 psi and it raises with rpm in lower gear so its fine. But I saw 19 psi on the highway while cruising 1400-1500 rpm. I put it in neutral and it goes back to 38-45.

Im afraid it will continu to lower too much now..

Camaro99SS

iTrader: (4)

Replace the oil pressure sending unit first or check the pressure with a mechanical gauge. Sounds like a classic case of a bad sensor.

Jason

Johnnystock

iTrader: (6)

I will replace it for sure because it seems the pressure is always fine when under 1100rpm (36-41 psi) and over 1900-2k rpm(31-38). Idle is strong at 38-41. PSI follow the rpm, but there is a dead spot around 1400-1600. I saw some peak switching from 26 straight to 41... really seems like a bad sensor now.

Thanks all

C6smackdown

iTrader: (1)

What kind of sensor are you using? I have built countless LS's for 17 years and have never seen an OPS have dead spots. They either peg to 130psi (OEM) or they flatline.
It wouldn't hurt to check it against a mechanical gauge though. There's a first for everything.

Johnnystock

iTrader: (6)

Its a summit racing sensor. PSI went as high as 55psi with the added oil..

On my way back home I did some WOT pull and the pressure was holding better after for a long time, even in the 'dead spot'.

Plus I could see some 1sec blip from 20 to 41psi while hanging in the dead spot.

I removed the stock unit. I wanted to run a 'tee' but the wait on the part took 2 months.

Johnnystock

iTrader: (6)

It went as low as 17psi 1500rpm but mostly at 20psi.

kinglt-1

iTrader: (26)

Has nothing to do with the oil...5w30 and 10w30 are the same when up to temp. Oil pressure should always rise with RPM even free revving.

C6smackdown

iTrader: (1)

I completely overlooked the "30" part. You are 100% correct on that. It was a case of answering BEFORE I read the OP.

Johnnystock

iTrader: (6)

10-04^^