1992 Isuzu 3.2 DOHC oil/hot issues. Oil recommendations?

[Bend3r]

I have a great 1992, Isuzu trooper 3.2 DOHC that starts and runs great with +55psi, no noise issues when cold outside, in summer or when run hard on the interstate at 75-80 the oil pressure drops to 20-30 psi at driving speeds and below 10 at idle, it makes horrendous noise like it’s coming apart, top end lifter rattle, but if it sits and cools off, it will run quiet an normal again. It seems to be backwards of the 3.2 SOHC noise issues. Nothing seems to be damaged as it has done it for over a year.

I added Lucas (be nice I’m new) trying to increase viscosity seemed to help a lot. But it would still rattle in the summer heat or ran hard on interstate. I was thinking of trying a Delo or Rottella 15-40 to see if it was just thinning out too much. I may add an oil cooler to see if that helps. I love this truck so much. If it ever dies I’ll just throw a new motor in it. I’ll keep it forever. I put a bunch of money into it. 5speed man, 4.56 gears, lifted and bigger tires, ARB winch and bumper and new paint.

 

[Krieg]

HPL oil. Lifters like lots of moly.

 

[Trav]

But they do not like MoS2, they can clog and make a racket.

 

[Brian123]

How many miles are on this vehicle and are you the original owner?

 

[SubieRubyRoo]

Op, I’d spend $300 on an oil cooler before I spent $3 on Lucas. But first I’d add an oil temp gauge and see how hot you are really dealing with- oil would have to be really thin to drop from 55 to 10. It will also tell you how many BTU you’ll need to get out of the oil, and guide how big of an oil cooler you need.

 

[Chris142]

The main,rod or cam bearings are worn. Assuming some oil galley plug is not missing. You can try 20w-50. It may help for a while.

 

[ripcord]

If you want to keep this rig long term, it wouldn't be a bad idea to pull the engine and rebuild it before the block "self ventilates."

 

[Fabulous50s]

You didn't say what oil you are currently using with those pressures.

 

[Passport1]

Looks like your truck is in the outback parked under a mulga tree and it's sporting a 'roo catcher'. Is it a RHD?

 

[Bend3r]

Looks like your truck is in the outback parked under a mulga tree and it's sporting a 'roo catcher'. Is it a RHD?

No left hand drive. I bought it a year ago to fit my family and gear. It has 200k. Unknown history but zero rust and runs like new till hot. I do not remember oil weight, 5-20 syn Mobil 1 I think. I then added Lucas a couple months later. Oil change is ready now and I’ll use a wix or Napa gold. Just trying to figure out best oil type. Something with zinc and goodies like HD oil. I need to see where I can add oil cooler. I don’t know if I have a place to tap yet. Need more research.

 

[Bend3r]

The main,rod or cam bearings are worn. Assuming some oil galley plug is not missing. You can try 20w-50. It may help for a while.

This is what I was thinking. I may be able to boost oil pressure with an Isuzu trick. I think I can shim a bypass somewhere. I’ve read about it. Worst case I’ll limp this motor as I find/purchase a rebuild.

 

[ripcord]

5w-20 is thinner than what was specified for this engine. They originally called for 5w-30, but I would try 15w-40 to see how that works.

 

[ripcord]

Here's a page from the 1992 Trooper workshop manual showing the recommended viscosity ranges for the 3.2l.


https://workshop-manuals.com/isuzu/...ifications/capacity_specifications/page_1148/

 

[Revving2Redline]

Some high quality boutique oil with esters and moly might help.

 

[Bend3r]

Some high quality boutique oil with esters and moly might help.

I would try it. Is there a zddp additive? I have No emissions check in my state. May even delete egr to stop carbon. It says 200k on the clock but it runs so nice it may have been rebuilt or less miles, I’ll never know.

 

[FCD]

Delo or Rotella 15w40 would be fine, even M1 15w50 if the OM allows for a 50 grade oil.

 

[ka9mnx]

5w-20 in a 1992 Isuzu with 200k?

 

[FCD]

No left hand drive. I bought it a year ago to fit my family and gear. It has 200k. Unknown history but zero rust and runs like new till hot. I do not remember oil weight, 5-20 syn Mobil 1 I think. I then added Lucas a couple months later. Oil change is ready now and I’ll use a wix or Napa gold. Just trying to figure out best oil type. Something with zinc and goodies like HD oil. I need to see where I can add oil cooler. I don’t know if I have a place to tap yet. Need more research.

You're running 5w20 in that 30 year old engine with 200k miles?? Why? No wonder you have oil pressure problems.

 

[Fabulous50s]

My thoughts exactly....5w20 and wonder why oil pressure is low. Minimum of a 10w30 maual even recommend 15w40.

The thinnies should read this thread.....

 

[Bend3r]

I’m going to try 20-50 rotella or synthetic equivalent.