Diesel Engine Oil Flush

[Snotter]

I was reading a truck forum the other day in which the topic of engine oil flushing was discussed (gas engines). Many were adding a small amount of diesel to their oil prior to changing the oil. They would then run the engine for a short bit prior to draining the oil. They claimed it was just as effective at cleaning the guts of an engines as the oil flush products sold in auto parts stores.

I've been buying the expensive oil flush products to flush my perkins 4-154 diesel when doing oil changes. Would adding a small amount of diesel to the oil in the engine significantly raise the probability of a runaway condition? If not, how much should I thin the oil?

 

[Don S/V ILLusion]

In the context of how tight your piston rings are, Clint Eastwood might ask "do you fell lucky punk, well, do you?

 

[Rob2435]

I have seen boats that have either fuel pump or fuel return line problems and let fuel enter the engine oil. I don't know if it cleaned the engine but it did thin the oil, which might be a reason to add it to the oil, let the engine run for a while, to mix and thin the oil, then change. Any of the engines that had fuel in the oil didn't "run away".

 

[Jake N Eggs]

Thinning the oil with diesel fuel allows the oil to drain off the components faster allowing marginally more oil to be removed at the oil change. Letting the engine sit for a while will accomplish the same thing, with one exception. Oil with the correct viscosity will remain on the wetted surfaces of the critical components thus protecting them during start up. Thinned oil that runs off these surfaces will leave the critical components exposed to increased wear during start up. The critical components are the main and rod bearings, oil pump, lifters, cam, rockers etc......

If you want a clean engine and proper protection change the oil more often and use high quality diesel engine oil. It comes with detergents built right in.

It would be an expensive experiment, in my humble opinion.

 

[Benny17441]

There we have it, everything is a trade off; it helps drain and remove more of the old oil but leaves parts partially unprotected upon start up. Does not make sense to use expensive cleaners though to get the same result.

 

[Ralph Johnstone]

Thinned oil that runs off these surfaces will leave the critical components exposed to increased wear during start up. The critical components are the main and rod bearings, oil pump, lifters, cam, rockers etc......

Jake, I didn't even think beyond the idea of "expensive oil flush products " as being just another engine oil scam. As you've pointed out, the idea of leaving your critical components exposed to excessive wear during start up (because of thinned oil) is just asking for trouble.

Change your oil frequently and allow the detergent to do its job. If you buy your oil on sale (Chevron Delo 400, 15W-40 oil for $11.97 / USG from Walmart) it's probably cheaper than the "expensive oil flush products "you're using now. Trust Chevron, Shell, and the other big guys, they're pros and know what they're doing when it comes to engine oil. They may be polluting the hell out of our environment, but they know engine oil.

 

[Maine Sail]

If you want a clean engine and proper protection change the oil more often and use high quality diesel engine oil. It comes with detergents built right in.
.

Bingo!!!

 

[Eddie7045]

Yeah, Ralph pretty much said it all. Over the years

half of what I learned about mechanics was undoing popular myths of shadetree mechanics. Crankcase oil gimmicks tend to be popular because people tend to put off changing their oil like they should and so look for gimmicks that make up for this but there are none.

 

[MSter]

Is there any benefit or harm to adding a cup or 2 of diesel when changing oil ? This was suggested somewhere else once as helping to get all or more of the contaminating sludge etc out. I haven't tried it but would like to .
Mike

 

[Eddie7045]

MSter, just change the damn oil. If it's really dirty

run it for a few minutes and change it again.

 

[kloudie1]

There was a time, probably ended about 1970's, when a flush might have done some good.. Those were days when gasoline had a lot of lead in it, diesel had a lot of "bad actors" in it, and the motor oil additives and detergents were nowhere close to what we have today.. That is where those ideas came from, a time when stuff was different.. I wouldn't add a flush today unless I'd gotten a bunch of water in the engine and made mayonnaise in the crankcase.. Otherwise, change the oil when it is hot enough to be uncomfortable to touch (110-115 F) and let it drain a while.. or suction pump then wait 15 minutes and pump again.. MaineSail posted some pictures of the valve train on his engine showing how clean today's diesel engine oils keep the engine..

 

[Maine Sail]

MaineSail posted some pictures of the valve train on his engine showing how clean today's diesel engine oils keep the engine..

Engine oil changed ahead of factory recommendation and only Rotella 15W-40 has ever been used. These shots were taken at:

Flush what..?

I am doing a valve adjustment next week and will snap some more pics.

 

[Snotter]

This is great stuff. Thanks all for the comments. I've always changed the oil no later than 75 hours. From now on I will make sure to let the engine stand for a bit after running it to thin the oil. I won't use engine flushes.

 

[Maine Sail]

This was taken on 8/1/2013. Engine has approx 3500 hours and was in-between oil changes. Still using only Rotella T 15W-40....

 

[Eddie7045]

Uh, yeah, I think we got it, Maine, ole buddy.

.

 

[sailaway78]

A couple of times

A couple of times I have " flushed " mine by draining existing oil, filling with fresh oil, running the engine for a few minutes and draining again. Basically just changing oil and filter twice. Don't think this really does much good, except in my mind.

 

[Snotter]

Re: A couple of times

My motivation for doing an engine flush was to lower the viscosity of the oil so that the oil extraction pump wouldn't take as long to suck the oil dry. My perkins 4-154 uses almost 3 gallons of oil. Even when I run the engine before changing the oil, it takes a lot of time to suck the engine dry.

In light of the comments provided in response to my post, I'll be avoiding using addatives to the oil for the purpose of flushing the engine. I'll also be running the engine longer to warm the oil and then letting the engine sit a while before extracting the oil. However, it takes so long to extract the oil that I suspect the issue of letting the engine sit is moot.

BTW, I am using the largest electric pump on a COTS oil extractor that I can find on the market. The pump draws some serious current at 12V. The problem is the rediculously small tube that is neccesitated by a small dipstick tube. If and when I repower, I am going to make sure the engine is plumbed for oil extraction.

 

[woodster]

This was taken on 8/1/2013. Engine has approx 3500 hours and was in-between oil changes. Still using only Rotella T 15W-40....

THAT IS THE BEST OIL ON THE PLANET!!!!!!!!!!!!!!!.......and they have the best anti freeze too

regards

woody

 

[captcoho]

My motivation for doing an engine flush was to lower the viscosity of the oil so that the oil extraction pump wouldn't take as long to suck the oil dry. My perkins 4-154 uses almost 3 gallons of oil. Even when I run the engine before changing the oil, it takes a lot of time to suck the engine dry.

In light of the comments provided in response to my post, I'll be avoiding using addatives to the oil for the purpose of flushing the engine. I'll also be running the engine longer to warm the oil and then letting the engine sit a while before extracting the oil. However, it takes so long to extract the oil that I suspect the issue of letting the engine sit is moot.

BTW, I am using the largest electric pump on a COTS oil extractor that I can find on the market. The pump draws some serious current at 12V. The problem is the rediculously small tube that is neccesitated by a small dipstick tube. If and when I repower, I am going to make sure the engine is plumbed for oil extraction.

Next time you "sucked" out all the oil, before refilling install a oil changing drain plug valve.
Put some oil absorbant "diapers" down on top of a plastic bag first. You may have a small mess to clean, but will make changing oil a lot easier and cleaner in the future... For example;
http://www.youtube.com/watch?v=VHIoQb2WPL0&feature=player_embedded

"
The Engine Oil Drain Valve has been tested and granted "Genuine Parts" status by 6 major motor vehicle manufacturers in Japan, including Toyota, Nissan, Mazda, Mitsubishi, Subaru and Isuzu. These approvals were not granted easily and gaining them was a testimony to the quality and durability of Engine Oil Drain Valve. In the United States, the Engine Oil Drain Valve is being installed at the factory level on some of the vehicles/equipment made by Ford, Kohler, Freightliner, Caterpillar, JLG, GEHL, Ingersoll-Rand, Sullair, Toyota, Case, Magnetek, Timberjack, Lincoln Electric, Vermeer, Baldor, Terex, Deutz, Phaser Marine Generator and etc. "

 

[Snotter]

Next time you "sucked" out all the oil, before refilling install a oil changing drain plug valve.
Put some oil absorbant "diapers" down on top of a plastic bag first. You may have a small mess to clean, but will make changing oil a lot easier and cleaner in the future... For example;
http://www.youtube.com/watch?v=VHIoQb2WPL0&feature=player_embedded

"
The Engine Oil Drain Valve has been tested and granted "Genuine Parts" status by 6 major motor vehicle manufacturers in Japan, including Toyota, Nissan, Mazda, Mitsubishi, Subaru and Isuzu. These approvals were not granted easily and gaining them was a testimony to the quality and durability of Engine Oil Drain Valve. In the United States, the Engine Oil Drain Valve is being installed at the factory level on some of the vehicles/equipment made by Ford, Kohler, Freightliner, Caterpillar, JLG, GEHL, Ingersoll-Rand, Sullair, Toyota, Case, Magnetek, Timberjack, Lincoln Electric, Vermeer, Baldor, Terex, Deutz, Phaser Marine Generator and etc. "

The quick valve is something I would like. I wonder if my perkins 4-154 has a drain plug on the bottom of the oil pan. If it did, it would be a ***** to get to on my boat. I would probably have to jack the engine up to get to it or pay someone who has more flexibility in his back than me to reach under the engine to install it. ...Come to think of it, I seem to recall seeing a big, plug looking bolt on the side of the pan. I've never considered cracking it since there would be no way to get a container under it to capture the oil. However, a quick valve with a nipple would allow me to plumb a tube of adequate diameter to the oil extraction pump. I will investigate further when I am next on the boat. Thanks for the suggestion.