Do all synthetic oils act as a cleaner?

Messages
153
Location
Arizona
Thread starter
I occasionally read about synthetic becoming darker quicker and/or causing leaks in older MPI engines because it loosens leftover deposits in engines that supposedly always used conventional. Wouldn't fresh conventional with the same additives do the same thing, or does the fancier base stocks of synthetic contribute to this cleaning far better?
 
Messages
24,807
Location
Upstate NY
Yes. But if you want to clean a less expensive synthetic changed more often is best. As always, the valve cover should be pulled to check for sludge.
 

CT8

Messages
15,408
Location
Idaho
FordCapriDriver said:
Some synthetic base stocks like PAO if i remember correctly have intrinsic solvent characteristics, others like Group III and Esters not so much.[/quote} Esters clean PAO and GPIII not so but then there are the additive packages.
 
Messages
2,023
Location
WY
The Ester or Group V is the base oil that is known to clean. You won't find much Group V ,if any, in off the shelf oil nowadays. If I had to guess it would be that there is no ester content of any amount in any mass marketed synthetic oil in America. It's probable the modern add pack may substitute some of Ester's characteristics used in the predominately Group III base oil found on the shelf at the local Walmart..
 
Last edited:
Messages
1,047
Location
Indiana (IN)
Originally Posted by FordCapriDriver
Some synthetic base stocks like PAO if i remember correctly have intrinsic solvent characteristics, others like Group III and Esters not so much.
Exxon Mobil has this to say about Group V base stocks The use of Synesstic™ AN base stocks or Esterex™ esters as PAO co-base stocks can offer the following benefits: • seal swell and additive solubility • improved lubricity • improved cleanliness • improved thermal and oxidative stability
 
Messages
153
Location
Arizona
Thread starter
Originally Posted by FordCapriDriver
Some synthetic base stocks like PAO if i remember correctly have intrinsic solvent characteristics, others like Group III and Esters not so much.
I figured group III would behave like group II in terms of cleaning. I bet it's each oil brand's high end line of oils that have a mix of PAO and whatnot that really do the cleaning. You can see it in the volatility rating and flow characteristics in -30° temps. What about GTL derived oils? I know Pennzoil Platinum cleaned the living trash out of one engine we got (a 1MZ-FE).
 
Messages
86
Location
USA
PAOs are Group IV and esters and alkylated naphthalenes are Group V. Group IV, PAO, fluids are more thermally stable than mineral oil and contribute less to deposits. However, they don't have any significant cleaning advantages over mineral oils. Esters and ANs tend to have better solubility characteristics which is why many PAO-based engine oils contain a low treat level of them. The 8-10% ester or AN in many synthetic oils improves additive solubility which is less than satisfactory in PAO fluids. Some suppliers may use Group III oil for additive solubility which doesn't contribute to cleaning. PAO and ester/AN oils will improve cleaning, but they probably will have little impact on existing carbon and varnish. They will solubilize sludge. These oils will also reduce deposit formation.
 
Messages
10,426
Location
Cincinnati, OH, USA
Some "conventionals", actually most, are synthetic blends including Grp. III bases-I still have a case of PYB 5W20 from the days when Shell was using GTL base in PYB, along with the old high moly formula (pre-SN+)-I would wager that it would clean as well as most lower-end synthetic oils.
 
Messages
42,893
Location
Ontario, Canada
Originally Posted by FordCapriDriver
Some synthetic base stocks like PAO if i remember correctly have intrinsic solvent characteristics, others like Group III and Esters not so much.
You've got that somewhat backwards. As the purity of the base oil increases with respect to catalyst derived and solvent dewaxed bases, the solvency and polarity decrease. So, Group I is the most polar of the traditional hydrocarbon bases and as you go up the chain, this decreases until you are at Group III where you have next to no solubility, which is only eclipsed by PAO, which is even worse. These bases offer better thermal stability and superior cold temperature performance (particularly PAO) but because they are so pure; so "neutral" they that an oil blended with them be dosed with something else to improve solubility. This is either a lower group base or something like POE. Esters have a great deal of polarity, which is one of the reasons Mobil uses them in their PAO-based formulations and even shows them in their blending guide, as they facilitate proper solution of the addpack and give the oil the ability to better keep contaminants and combustion byproducts in solution. GTL, being a Group III product, would be as bad as VISOM and other group III bases, if not worse, in terms of solubility and is probably as close as you can get to PAO in that department.
 
Messages
2,393
Location
pa
more than anything $$$$$ determines whats in oils + all oil blenders strive to meet specs using the least costly base oils + add pack that meets a spec + classification. in most cases its the additives + since diesel oils use more even basic diesel oils clean better. only real synthetics PAO + Esters are totally clean because they are man made in labs not from dirty CRUDE oil!!
 
Messages
1,405
Location
South Carolina
Group IV PAO has the lowest solvency of any oil group and also the harshest on seals. This is why you won't find a straight PAO oil. It will have some amount of group III, ester, or napthalene to give it some solvency and help condition seals. The group III and IV synthetic oils actually have less cleaning ability than conventional group I and II oils because of that lower solvency. Solvency is what breaks down sludge so it can be picked up in suspension and filtered out. The additive package has little to do with this. A common misconception is that detergents clean the engine, but that's false. Detergents keep the oil clean as a way of sludge prevention, but they do not remove sludge that's already there. If you want to clean up sludge from your engine, the best way to go is an oil with a lot of ester. This is the basis for Valvoline Premium Blue Restore (VPBR) as it's ~60% ester.
 

4WD

Messages
13,506
Location
Texas
I'm thinking the 30-40% that is not PAO in M1AP is a cocktail of all of the above … must have been endless combos tested in development … they might have learned some things usable to M1 EP which I think they can just fill the EP bottles with AP once they give up.
 

CT8

Messages
15,408
Location
Idaho
Originally Posted by BigCahuna
Do they sell blended oils only for people that don't care about keeping their motors clean?.,,,
proper oil change intervals work wonders. What does it matter when you d\get the cat towed to the junk yard with a clean engine?
 
Messages
912
Location
Pennsylvania
Originally Posted by Loobit
I occasionally read about synthetic becoming darker quicker and/or causing leaks in older MPI engines because it loosens leftover deposits in engines that supposedly always used conventional. Wouldn't fresh conventional with the same additives do the same thing, or does the fancier base stocks of synthetic contribute to this cleaning far better?
I think you have it backwards here: Synthetics are far less likely to leave anything behind that needs cleaning. You don't run a synthetic to clean your engine; you run a synthetic to keep your engine clean.
 
Messages
12,877
Location
ROCHESTER, NY
I always thought that it was the extra amount cleaning additives(Calcium & Magnesium) in the synthetic oil that allowed for better cleaning compared to conventional oil.
 
Messages
1,405
Location
South Carolina
Originally Posted by Char Baby
I always thought that it was the extra amount cleaning additives(Calcium & Magnesium) in the synthetic oil that allowed for better cleaning compared to conventional oil.
Synthetic oils, with the same API rating, don't contain any more nor less detergents than their conventional counterparts. Even if they did, detergents don't clean the engine.
 
Messages
572
Location
Ohio
My post is unscientific but I did have a varnished dipstick come clean with a run of Mobil 1 10-30 HM. I'm picking up an engine that set for yrs with only 30k and am gonna runs a couple of short intervals of shell clean engine and then switch it to Mobil 1 AP and change it once a year as long as it doesn't use any oil.
 
Messages
147
Location
East Europe
While generally not having more detergents/dispersants than semi-syn oils, synthetics just dont have the sulphur and impurities to detract from the oils acid neutralizing capabilities or to form new deposits/sludge in the same volume, if you do a reasonable OCI. So the same dose of calcium/magnesium detergents takes a little of the old stuff to the filter. If anyone wants to read up, this paper here had some good stuff: https://link.springer.com/article/10.1007/s40090-017-0128-x
 
Last edited:
Top