What motor oil does the best job of cleaning?

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brages

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Suppose you had an engine with a bit of deposits in the top end and you wanted to use an oil that would help clean it up. Or maybe you bought a used car with unknown history and you wanted to clear out any crud that may have built up from missed maintenance.

Are some motor oils better for cleaning up an engine than others? If you suggest one, please give a reasoning as to why it cleans well.
 
Oils (no matter the brand) are not designed to be cleaners, they are designed to keep engines clean. About the only oil I've ever seen the manufacturer claim to actually be able to do some cleaning was Mobil 1 0w-40.

If you have reason to believe you have some significant deposits, there are ester-based products specifically formulated to clean like @High Performance Lubricants engine cleaner.
 
"They say" and I've experienced Mobil 1 full synthetic take a lot of crud out with it in 1,000 miles. This is my experience with a used engine with 86k miles on it I installed in a vehicle. I've never had an oil come out that dirty that quick. Maybe anecdotal and maybe any good synthetic would have done it.
 
OVERKILL said:
Oils (no matter the brand) are not designed to be cleaners, they are designed to keep engines clean. About the only oil I've ever seen the manufacturer claim to actually be able to do some cleaning was Mobil 1 0w-40.

If you have reason to believe you have some significant deposits, there are ester-based products specifically formulated to clean like @High Performance Lubricants engine cleaner.
Click to expand...

I strongly believe this after a lot of years of study and application.

With regard to ester oils, here's some visual proof. Here's an engine w/an unknown but suspect history that I acquired.

Filter deposits after 6,500 mi of Castrol 5w-30 full synthetic:

Volvo 1275810 (Mahle) filter doing it's job - thank goodness (ugly stuff)!

This is a dealer-installed Volvo filter - Mahle I believe (made in Austria is on it though not visible). Installed 6,500 miles, castrol 5w-30 synthetic (dealer installed in 11/2016) 2004 S60 2.5t awd, 133k mi. There was a tiny bit of thickened oil in the bottom of the filter housing (it sits...
bobistheoilguy.com

Dramatically more cleaning after 8,500 miles of Mobil 1 10w-30 HM + Lubegard additive (ester oil base):

Bosch Workshop cartridge filter from a white block Volvo engine

This is a Bosch Workshop filter, 72066 for a white block Volvo engine. It was in a 2004 Volvo S60 2.5 turbo for 13 months and 8,500 miles, with Mobil 1 10w-30 HM and 10 ounces of Lubegard Biotech additive. Looks like the filter did it's job, but not with ease. I definitely did NOT intend to...
bobistheoilguy.com


I will be doing another oil change after a further ~7,500miles and another run of M1 10w-30HM and Lubegard in March I estimate, and posting it.
 
In early 2018 I got my mom's 2000 Forester after she died. When I got it here I immediately changed the oil (not changed for a few years and when changed dino oil, but also not driven much) with M-1 5w-30. Then my son used the car to drive to Mesa Verde. When he got back, around 1,000 miles round trip, I checked the oil and it was brown. That is a lot of cleaning, but also a pretty dirty engine. My father insisted that 5,000 mile OCIs with dino oil was fine.
 
OVERKILL said:
Oils (no matter the brand) are not designed to be cleaners, they are designed to keep engines clean. About the only oil I've ever seen the manufacturer claim to actually be able to do some cleaning was Mobil 1 0w-40.
Click to expand...
Is that this 0W-40?

1643233661808.jpg
 
brages said:
Suppose you had an engine with a bit of deposits in the top end and you wanted to use an oil that would help clean it up. Or maybe you bought a used car with unknown history and you wanted to clear out any crud that may have built up from missed maintenance.

Are some motor oils better for cleaning up an engine than others? If you suggest one, please give a reasoning as to why it cleans well.
Click to expand...
Like Overkill said Mobil 1 0w40 does a good job, on engine with varnish I have seen the oil come out looking more like old ATF than engine oil, it is removing the varnish.
I have posted this many times but this is proof. This engine had quite a bit of varnish in it, if you look at the oil drops you can see a red tint to it, that dissolved varnish, the piston that still looks dirty is because that one is partially covered by the pick up tube but it too is coming clean like the ones on the bottom of the picture. No flushes were ever used on this engine.
All that being said I am going to use HPL oil and cleaner in a car that will run again in spring that has a similar varnish issue.

SAM_1118.JPG
 
Trav said:
Like Overkill said Mobil 1 0w40 does a good job, on engine with varnish I have seen the oil come out looking more like old ATF than engine oil, it is removing the varnish.
I have posted this many times but this is proof. This engine had quite a bit of varnish in it,

View attachment 86238
Click to expand...
Please tell us the length of time and miles of the OCI? Was this result from just one OCI? What engine is it, and how old is it?

It may be a bit of a guess at this point, but do you think the Mobil1 will afford a gentler cleaning than the HPL?
 
Shel_B said:
Please tell us the length of time and miles of the OCI? Was this result from just one OCI? What engine is it, and how old is it?

It may be a bit of a guess at this point, but do you think the Mobil1 will afford a gentler cleaning than the HPL?
Click to expand...
It was a GM 3800 gen II non SC, OCI was every 5K and this took about a year or maybe a year and a half and 3 OCI. I think the HPL will do the same or better in a shorter time and I cant see it being anymore harsh as it also a formulated engine oil. IMO expecting a grungy engine to be spotless in one OCI is not realistic, it takes time regardless of what you use.

After PM I have had with HPL and the post Molecule and others have made about their products I am definitely going to run their cleaner and engine oil and see, its not about the money its about the results. My OCI on any car I own is about once a year or 5K so $100 a year per car for an OC is not bad at all.
 
Ive seen a number of posters ask about cleaning out an engine with a good oil. While that will help, it wont do that great of a job all on its own. Ive often seen Liqui Moly Pro Line Engine Flush recommended for such a thing. When you change your oil, add a can of the engine flush and run it without driving or revving the engine for 10 minutes then drain. Change filter and fill with oil as usual.

I had really good luck with Hot Shots Stiction Eliminator once. Its like the HPL Engine Cleaner where you run it for an entire OCI, rather than at the time of the change. I thought my Caravan engine was fairly clean. I was amazed to see all that it pulled out and how dark the oil was when I changed it. Then again, it was a shop use vehicle for a good 10 years and always got the oil changed at the local mechanic for as cheap as possible and ran to 5k, sometimes 7.5k. That may have had something to do with it.
 
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