oil contamination

[ace58]

The oil pressure drops from 35-40psi to 20 psi 6-800 miles after an oil change. The dipstick level and the oil on it are fine. In the drain bucket there is not an odor, and after cutting apart the oil filter, no metal or filings.

The engine has 3500 miles on it and the turbo, injector pump, injectors, lift pump, and fuel filter are new. I have a remote oil filter and an external thermostatically controlled by-pass to the oil cooler piped with -10 hose and fittings due to issues with the filter boss on the block.

The oil is Rotella full synthetic 5/40. I am going back to Mobil 1 15/50 and have ordered Amsoil 15/40 for the next change. Ant thoughts or ideas welcome.

[Barry Nave]

I'v noticed this on my truck after installing the Amsoil duel-By pass system though it only drop's down to 25lbs at idle and eng. up to temps. Greg says not to worry,idle can be lower and comes back up off idle.
Your case though is interesting that it does it after 6-800 mile then stays at 20lbs. :confused:
I would want to install a Mech. gage to confirm the readings.

[ace58]

The readings are much better with the Mobil 1 15/50. Cold start is at 60 psi and, although it drops after warm up, operating pressure is at 35- 40, and 25 idle.

[Barry Nave]

ace58
I've not seen a 15W-50 CH4 rated oil. Moble 1,this must be a syn. oil right. Where did you fine this oil?

[tom.mcinerney]

>>external thermostatically controlled by-pass to the oil cooler

Was this to get around the OEM cooler lines?

[ace58]

15/50 Mobil 1 is a full synthetic oil.

The thermostatically controlled bypass limits flow to the oil cooler before oil reaches operating temperature.

After discovering a cracked block, I bought an engine with less than 500 miles that had a leak at the oil filter boss, and was replaced under warranty. The leak occured when the oil filter adapter was under pressure.

The solution was the fun part.

The internal valves that protect against a plugged oil filter and resistance of cold oil into the external cooler were removed, the tappings at the boss plugged (except for the center), the remote oil filter piped in series with the oil cooler and thermostatically controlled bypass piped in -10 hose and fittings.

The factory oil cooler passages are adequate but small and the concern was with cold oil in the winter, why risk stressing the oil pump

[DmaxMaverick]

I would not recommend using Mobil 1 15-50 in any of our Diesel engines. It is primarily rated SJ. It is also rated CF/CD, which is an outdated Diesel rating, by more than 25 years. Your oil should have a rating of at least CG, but CH or CI are better options. All older GM Diesels came with a recommendation of a CG rating. Later GM Diesels were recommended CH, or CI in the last couple years.

View Mobil's product info on this oil at: Mobil 1 15-50 product page. (http://www.mobiloil.com/USA-English/MotorOil/Oils/Mobil_1_Extended_Performance_15W-50.aspx)

Use it if you must, but it appears it was not designed as a Diesel motor oil. There are better options out there, and probably for less $$. Also, I think a 50 weight oil is too high for a Diesel engine, regardless of its W rating (15, in this case).

[ace58]

Thanks for the input. What do you use?

[Barry Nave]

At Wal-Mart I get the STP red bottle and use half at each oil change per Dr. Lee. Fourm, Ask Dr Lee.
I'm running Rotela T Heavy Duty 15-40.
I do see that Wal-Mart also has the Moble 1 15-40 CH4-CI in 5qt. jugs at less than $20 each.
Not bad I thought. This would be better than the 15-50 and the Rotela T. I'll give the Moble- 1 a try now that I know where to get it.