Bouncing oil gauge

[1983/300CD]

I just took a 60-mile trip on the highway, and when I got off and stopped at a light, I noticed the oil gauge at between 1 and 2 (usually at 2) and it was bouncing. That doesn't seem good. Any ideas?

Thanks,
Greg

[Sugar Bear]

Not uncommon and I'm not sure it's a problem. Some have attributed it to the two bad O-rings on the bottom of the oil filter cap tube.

Won't cause this problem; but, you are using a C rated oil and quality filters such as Mahle, Kinect, or MBZ correct?

Good luck!!!

[1983/300CD]

Rotella T5 synthetic blend, and... could have been an STP filter.
But I didn't change the o-rings last time I did an oil change. I'll make sure to do that.

[Diesel911]

Originally Posted by 1983/300CD

Rotella T5 synthetic blend, and... could have been an STP filter.
But I didn't change the o-rings last time I did an oil change. I'll make sure to do that.

The last time I saw an STP Oil Filter it was made in India (it was the same as the Indian mad Purolator oil filter). I cut one apart and they are poorly made. I would acquire a better filter.

I have never had mine apart but down there where the 2 O-rings are there is a spring-loaded valve. One of our members said that he had a low oil pressure issue, and he dissembled the valve and fond some of the cotton filter media that is in the top portion of the oil filters stuck in the valve.

[Sugar Bear]

FWIW, I tried the synthetic in my 617 motor and it sounded so different I changed it back to 15W-40. I would not use an STP filter only Mahle, Knecht, Bosch, or MBZ.

Good luck!

[1983/300CD]

The Rotella 5 is 15-40, and from what I understand, the addition of just a little bit of synthetic gives then the right to call it a "blend", and also provides many of the desirable properties.

I decided to adjust the valves and change the o-rings in the filter stem, but now the oil pressure spiked at 3 while at idle. When I shut it off, the pressure went down slowly, hung out at .5 bar for a second or two, then dropped.

Do I have an oil obstruction somewhere? What could be going on here?

[Sugar Bear]

Sounds normal. There is a passageway in the tube of the oil filter cap that could be blocked or restricted. I'd clean mine periodically with brake cleaner and compressed air, wear eye protection IT'S MESSY.

Didn't know the blend is 15W-40, what I had in mind was 5W-40 full? synthetic, was ages ago.

Good luck!!!

[1983/300CD]

Typically, the car held at 2 bar idling, and dropped to 0 as soon as I cut it off. I can check the filter cap tube for problems. Just so long as there isn't an oil passageway in the engine somewhere that is obstructed. I had an issue with a couple of cam lobes getting scraped up a little. I polished them smooth and cleaned out the oil squirter tube above them. That was a couple of years ago. Is there anything like an engine flush that I could try? I've heard of putting diesel fuel into the oil, but also heard that was terrible. I sure would like to get rid of any extra sludge or whatever might be in there.

[Sugar Bear]

I'd stick with short interval diesel rated oil changes on a HOT engine. I doubt there are restricted passages elsewhere. The problem with flushes on old engines is that they could cause problems with oil cooler hoses, rear main seals etc.

IF I were to use a flush I'd use a LiquiMoly product.

Good luck!!!

[chasinthesun]

If you want to clean the inside of the engine I would just increase your oil changes, say at 2500 miles . Change it hot but not right off the highway hot.

[vwnate1]

Fully synthetic oils will dissolve any sludge and get it into the filter P.D.Q. .

Be aware if your engine is really sludgy (?!plugged oil nozzle ?!) it's wise to not run further than 100 miles before doing a hot oil & filter change .

HOT oil changes are what keeps your engine clean inside .