What oil for 555a engine?

[Airman89]

I can’t seem to find the answer for the best oil to run in the 555a engine. I did an oil change filling it with rotella 15w-40 but the oil pressure is low (if my gauge mechanical gauge that I plumbed in is correct). I know this could mean pump or other it needs the lower end rebuilt but I’m just wondering if a 20w-50 oil would work in these engines?

I have a manual and know that it states 15w-40 for my temperature range here in Ohio but I’m not comfortable running it when it drops down to about 17psi at 2000rpms. I seen that an SAE 30 oil maybe work too but my thoughts were that a 20w-50 would be a better fit. What are your thoughts?

Thanks,

Adam

[Jim B]

15W40 should be fine. If the oil pressure can't be held with 15W40, using heavier oil to raise pressure only hides the problem for a time, at best. JMHO.

I would start by confirming that your current gauge is correct. You need a gauge known to be accurate (often called a master gauge) to check the oil pressure. Your Technical Manual should give you the specified oil pressure at high and low idle. I am thinking it is something like 50 psi (+15) at high idle and 15psi minimum at low idle. Did you plumb the new gauge in the same as the old one?

[Airman89]

Yes I plumbed the harbor freight tester gauge in the same location as the original gauge was plumbed in. The original gauge was reading low and my harbor freight gauge reads low so I’m assuming this must be correct.. I replaced the pressure relief spring and cleaned out the oil cooler last year.

There was a weird magnetic sticker on the side of the hood that said “replace oil line before removing” which I thought was weird, I have no idea what that’s about. It was on there since I purchased.

So all I would be left with is the oil pump or low end needing rebuilt then? Or are there any other possible places to look for oil restriction or pressure bleed off points? And chance I could lose pressure at the turbo? I have no blowby or smoke out of the exhaust.

[Jim B]

If the Harbor Freight gauge is correct and matches the reading of the crawler's gauge, oil pressure is low. If this had an engine rebuild 200 hours ago and oil pressure is way below the spec, something related to the rebuild could be suspect.