Using thicker oil

[csheath]

My MEP803A has always had marginal oil pressure. After it heats up it settles in around 18 PSI. I have a manual gauge added for reference and it mirrors the reading on the panel gauge (when that works).

I am on day 4 of continuous running and this morning right after I topped up the fuel it was reading 12 PSI and shut down for low oil pressure. I let it sit a while, restarted, and it came back to it's typical 18 PSI and has continued running.

I am running 15W40 diesel oil in it. It is on it's original oil change from purchase so I should change it anyway. I have put about 250 hours on it since the last change. Hour meter is at 2856 hours.

I am thinking about trying Castrol Classic 20W-50 with high zinc and possibly adding an oil thickener. Anybody use thicker oil to buy more time without rebuilding?

 

[WWRD99]

My MEP803A has always had marginal oil pressure. After it heats up it settles in around 18 PSI. I have a manual gauge added for reference and it mirrors the reading on the panel gauge (when that works).

I am on day 4 of continuous running and this morning right after I topped up the fuel it was reading 12 PSI and shut down for low oil pressure. I let it sit a while, restarted, and it came back to it's typical 18 PSI and has continued running.

I am running 15W40 diesel oil in it. It is on it's original oil change from purchase so I should change it anyway. I have put about 250 hours on it since the last change. Hour meter is at 2856 hours.

I am thinking about trying Castrol Classic 20W-50 with high zinc and possibly adding an oil thickener. Anybody use thicker oil to buy more time without rebuilding?

Dang that's a tough spot to be in if you need it right now. Putting in the thicker oil can get you by in a pinch. You won't get that much more psi but it might run longer without dropping. I've used that motor honey before on a few engines in the past and can't see it hurting anything. The zink part not sure if that will do anything since I think the lifters are roller not flat tappet. Either way I hope it sticks together long enough for you to make it through whatever you got goin on!

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[DieselAddict]

As the oil runs its viscosity drops. If you know its going to be days more of running then do an oil change with thicker oil.

More than anything as soon as the critical event is over you need to get to the bottom of the oil pressure problem. Could be something as simple as a partially stuck oil bypass valve.

 

[Scoobyshep]

Thicker oil can work but it's a bandaid at best. Adding zinc Won't do much either. If I had to make a suggestion it would be to find a single weight oil and add a stabilizer like Lucas.

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[Mainsail]

If it were me I'd go with a quality straight 30 weight oil. I don't think multi viscocity oil is bringing much to the party, especially in FL.

 

[Digger556]

If it were me I'd go with a quality straight 30 weight oil. I don't think multi viscocity oil is bringing much to the party, especially in FL.

Just make sure it's diesel rated 30wt, not gasoline. Diesel oil has more detergents and higher zinc.

 

[87cr250r]

Straight 30w diesel oil is rare. 40w was the standard grade. There is a 20w40. It's zinc free for engines with silver faced bearings. Runs fine in a John Deere 4045, though. Maybe it's not so good if you have a flat tappet cam.

 

[Digger556]

Straight 30w diesel oil is rare. 40w was the standard grade. There is a 20w40. It's zinc free for engines with silver faced bearings. Runs fine in a John Deere 4045, though. Maybe it's not so good if you have a flat tappet cam.

Rotella T1 30wt comes to mind. Readily available at box stores.

 

[Coug]

In theory the 15W40 is thicker than the 30wt oil at higher temperatures, so not sure how that would increase oil pressure.
I know on the oil Detroit 2 stroke diesels 15W40 would smoke and burn, where straight 40wt oil worked just fine.

A straight 40wt or 20W50 would be the next step thicker than 15W40. Considering the location, it's unlikely you'll be getting into temps too low for 40 weight, but if you do you can always keep a jug of it on hand and do an oil change before running it.

I wouldn't recommend doing both the 20W50 AND an oil thickener at the same time at first. Do either one or the other, or possibly experiment with the thickener with the oil that is in there first to see if it brings up the oil pressure at all before you do the oil change, so if it gives results you don't like you're not out an entire oil/filter change; just the thickener cost (not that an oil change is very expensive in these things)

 

[Triple Jim]

I know on the oil Detroit 2 stroke diesels 15W40 would smoke and burn, where straight 40wt oil worked just fine.

Right, 15W-40 is SAE15 with additives to keep it about as thick as SAE40 when hot. SAE40 has longer molecules than SAE15, so it doesn't fit between things like rings and cylinders as easily as 15W-40. My log splitter with an old B&S engine will burn 10W-40 oil fairly quickly, but doesn't burn much straight SAE40 at all.

 

[rickf]

You really need to think of it realistically. The motor is toast so trying to justify using top grade diesel oil in it now is like bolting the door after the horse has has left the barn. You can go with a straight grade heavier oil like a 40 wt and hope for the best but nothing you do is going to bring the oil pressure back without tearing into it. A short run on straight weight will not hurt it. Just use brand name oil and not wally world special.

 

[Guyfang]

Attached is the LO. It tells you what to use. You live in Florida. The chart says 30 wt in temps above 32+ Degrees. The army spent a lot of money to figure this out. I would do what the chart says. Its all we used in the Army, and worked just fine. Even in weather under 32+ degrees.

 

[rickf]

Guy, The Army spent a lot of money "figuring" out a lot of things. Doesn't always mean it was right, just meant it fit in the budget. I know that in the late 80's early 90's they converted to using 15W-40 diesel oil in all of their reciprocating engines. It was found to have the additives needed to work with the flat tappets while gasoline rated oils were getting away from them and it was also found to be much cheaper to be able to buy millions of gallons of one grade of oil instead of one amount on one grade and a different amount of another grade and then having to allocate all kinds of different amounts to different bases. New way, one oil, how many drums you need? Supply guys just go to the warehouse marked Motor oil and grab any pallet, no more searching for the right ones or worrying about sending the wrong stuff. There is no wrong stuff. When you think about it by that time period most all of the smaller gasoline powered stuff was gone. You still had the Hummers and on base Ford pickup which were all diesel and specified 15W-40 anyway. And the gensets, which seem to have done quite well on it. I run it in all of my older gasoline engines.

 

[csheath]

My morning crisis was averted with a 30 minute cool down. After that it restarted and ran 6 more hours until our power was restored. I'm thinking it just thinned a little more when I opened each door for the morning inspection for leaks. It had been running for 50+ hours continuous at that point. My temperature check was 178 at the thermostat housing and no leaks so it wasn't overly hot.

The oil specification in TM-9-6115-642-24 reads 30w OR 15-40. Given the fluctuating climate I live in I chose the 15W40. I'm in North FL and we have some 100 degree days in the summer and see some winter temps below freezing.



I may order a side cover gasket and inspect the oil pressure relief valve when I change the oil.

This machine has run more than 250 hours in the 7 years I've owned it at 18 PSI hot. I'm not going to do a complete tear down due to a 30 minute shut down. Like I said, it's due for an oil change so that is the first thing I should do. I don't think 20W50 will hurt it and I may try that anyway. At least I know the low oil pressure safety switch is working.

 

[Digger556]

18 psi is really low. Unless its just the pressure relief, your engine is on borrowed time.

 

[csheath]

18 psi is really low. Unless its just the pressure relief, your engine is on borrowed time.

It's borrowed 7 years worth of outages at that pressure.

 

[WWRD99]

My morning crisis was averted with a 30 minute cool down. After that it restarted and ran 6 more hours until our power was restored. I'm thinking it just thinned a little more when I opened each door for the morning inspection for leaks. It had been running for 50+ hours continuous at that point. My temperature check was 178 at the thermostat housing and no leaks so it wasn't overly hot.

The oil specification in TM-9-6115-642-24 reads 30w OR 15-40. Given the fluctuating climate I live in I chose the 15W40. I'm in North FL and we have some 100 degree days in the summer and see some winter temps below freezing.

View attachment 904956

I may order a side cover gasket and inspect the oil pressure relief valve when I change the oil.

This machine has run more than 250 hours in the 7 years I've owned it at 18 PSI hot. I'm not going to do a complete tear down due to a 30 minute shut down. Like I said, it's due for an oil change so that is the first thing I should do. I don't think 20W50 will hurt it and I may try that anyway. At least I know the low oil pressure safety switch is working.

Glad you made it through that. Maybe you got some bugs in the radiator too?? Like radiator might be a little clogged? Hopefully the last no power issue until you get it buttoned down!

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[87cr250r]

How hard is it to drop the pan on the engine? One could plastigage the bearings. If they're found to be worn, roll in a new set.

 

[2Pbfeet]

My morning crisis was averted with a 30 minute cool down. After that it restarted and ran 6 more hours until our power was restored. I'm thinking it just thinned a little more when I opened each door for the morning inspection for leaks. It had been running for 50+ hours continuous at that point. My temperature check was 178 at the thermostat housing and no leaks so it wasn't overly hot.

The oil specification in TM-9-6115-642-24 reads 30w OR 15-40. Given the fluctuating climate I live in I chose the 15W40. I'm in North FL and we have some 100 degree days in the summer and see some winter temps below freezing.

View attachment 904956

I may order a side cover gasket and inspect the oil pressure relief valve when I change the oil.

This machine has run more than 250 hours in the 7 years I've owned it at 18 PSI hot. I'm not going to do a complete tear down due to a 30 minute shut down. Like I said, it's due for an oil change so that is the first thing I should do. I don't think 20W50 will hurt it and I may try that anyway. At least I know the low oil pressure safety switch is working.

If you are the curious sort, you could take an oil sample for testing when you do the oil change to see what viscosity you are at.

Trying to change to a 20W50 oil won't do much for you. The difference in viscosity is not much when hot. Since your unit has always had low oil pressure, I would be thinking a stuck bypass, like @DieselAddict, or a worn oil pump. How many hours are on your unit, and how many on this oil change?

When oil gets hot, it thins out out; notice the small difference between 10W40 and 10W60;

And now 10W60

Signifcant differences when cold, but at operating temperatures, almost none.

Thicker oil won't solve whatever issue you are having in my opinion.

All the best,

2Pbfeet

 

[rickf]

You could have the oil sample tested to tell you the condition of the engine.