Deposits?

[con carne]

We all know that the gap between synthetic oils and petroleum oils has narrowed significantly in past years, and I wondering.......is there still an area where synthetics show a benefit over petroleums (yes even Group III's) in the way of possible reduced deposits (carbon-ing) in the ring-pack, for example? Is this something that that actually happens anymore with petro's or is it a thing of the past?

 

[con carne]

Do you think it has more to do with additives than basestock?

 

[VaderSS]

It's a combination of additives and basestock. Scheaffer's shows that a Very good additive package can make a good oil without going to true synthetic basestock, but for over-the-counter oils, it seems that the better the basestock, the better the oil. I know that if you get deep into it, certain OTC oils within a class will do better for each individual application, but you are pretty safe considering each OTC oil within a class to be near equivalent to each other.

 

[Patman]

I think that with the new SL standards being more strict, all oils will provide good cleanliness, provided you don't go way over a normal interval with them (for instance, don't try to go 10k with an off the shelf $2 oil)

 

[buster]

I guess the only reason I'd still consider a good synthetic over a dino oil, even though wear maybe identical, is to prevent deposits.

 

[JohnnyG]

This is a very good question for owners of vehicles that are reported to be more susceptible to sticking ring packs. You need to make a few assumptions first to even consider that there MAY be an advantage to using synthetics. Assumption #1: GM's story about several of it's engines (ie saturn, caddy) use oil due to stuck rings. In reality, this is not limited to GM engines, they're just the only ones that I've heard the story from. Assumtion #2: The stuck rings are caused by high temps in the ring area due to engines designed for high fuel mileage/low emissions and the placement of the rings higher up on the (minimally sized)piston skirts. Assumption #3: That the VII's in non-recommended (wide viscosity range) dino based lubricants are the REAL culprit in sticking the rings. Yes, carbon in a way, but carbon from the polymer based VII's burning in that high temp area. Soooo, If you can believe all that, and I know some don't, and a synthetic oil, due to it's nature, requires NO or very little VII's..then I would say there is an advantage to using synthetics. And this actually goes against GM's recommendation to use dino in most cases to keep cost per mile down. I hate to keep bringing this up, but can anyone say which oil has the least VII's in it? Wouldn't it be a parameter to consider when choosing an oil for a specific engine? Shouldn't it get at least an honorable mention in an oil analysis or on the side of the oil bottle?

 

[Palut]

Wasn't the placement of rings higher up on the piston to help with emissions done on big diesel engines, not on gas engines?

 

[JohnBrowning]

Palut, I have no idea about the big diesels but cars have been doing this for a while. GM,DC amd Toyota have all done this. The degree to wich they have done it varrys a lot. Here is my take on the VII's adn convetional oil. If you insist on running cheap 5W30 expect your rings to stick on newer engines and to have consuption issues! If you are useing a decent 10W30 I would think you would be ok. NOAK volitility is a huge issues. The more of the oil that is burning off the more deposits you will have. The only way to use a 5W30 in my book is to use a synthetic and I still do not like them! I do not think all VII's today are equally evil in this reguard! It is always better to not have any VII's in your oil but their are ways to deal with them. One way it to do frequent oil changes. THe next way is to use Lube COntrol to keep them in check.

 

[Blue99]

quote:

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That the VII's in non-recommended (wide viscosity range) dino based lubricants are the REAL culprit in sticking the rings. Yes, carbon in a way, but carbon from the polymer based VII's burning in that high temp area.

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So in a well maintained, clean engine, with oil that is not carrying a high load of contaminants & fuel dilution, the rings will stick solely due to the VI improvers in the oil?

 

[Blue99]

quote:

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Here is my take on the VII's adn convetional oil. If you insist on running cheap 5W30 expect your rings to stick on newer engines and to have consuption issues!

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Aren’t we getting a bit far out there with this statement? Yes, the lighter base oils in a 5W-30 generate a higher Noack for the finished oil and high temperature oxidation is an issue. But even a “cheap” 5W-30 with a GF-3/GF-4 rating has passed the Sequence IIIG test. The parameters are 3600 rpm and 300 F for 100 hrs. Up to 4.6 L of makeup oil is allowed. Piston deposits must pass an established baseline and no hot stuck rings are allowed. So why would a "cheap 5W-30" automatically generate ring sticking in an engine that has no other issues?

 

[Blue99]

Thanks for the report on the Taurus, 1stTruck, but it should be noted that during the 90's, you no doubt ran quite a few gallons of GRP 1 oil thru that engine. Starting with GF-2, the push has been towards lower Noack volatility and this has generated the use of better adds & higher VI index base oils.

 

[JohnnyG]

quote:

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quote: -------------------------------------------------------------------------------- That the VII's in non-recommended (wide viscosity range) dino based lubricants are the REAL culprit in sticking the rings. Yes, carbon in a way, but carbon from the polymer based VII's burning in that high temp area. -------------------------------------------------------------------------------- So in a well maintained, clean engine, with oil that is not carrying a high load of contaminants & fuel dilution, the rings will stick solely due to the VI improvers in the oil?

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You are throwing a lot of "apples to oranges" comparisons into that statement. Could a "high load of contaminants" cause the rings to stick? I don't know. Does fuel dilution cause the rings to stick? Don't know that either. And finally "solely due to the VI inmprovers...." That solely word gets me...in those engines that are reported to be prone to stuck rings due to the piston design.....a definite maybe. All I know is I'm not going to be putting any 0W-50 anything in my Saturn until I find out how much VII is in it.

 

[1sttruck]

I did the 3k oil chnages, typically at the dealer, in our 93 Taurus, and at a bit over 100k miles it was running rough enough that I considered an engine oil flush. Instead I started using a home brew synthetic blend, and the engine smoothed out on the first batch. I've assumed that it was due to sticking lifters but perhaps it was sticking rings, although oil consumption wasn't that high. This was interesting as even though I adhered to recommended oils and change intervals I still ended up with some sort of deposit problem. One 'theory' I've developed is that deposits form because by definition they're not soluble in the oil being used, and that it may help to change oil brands on a regular basis in an attempt to minimize deposits. Perhaps a simpler method is to use a HDEO or PCMO/HDEO blend, which is what I started doing after I got a diesel and wanted to reduce the oils that I keep around. I've run across articles that state that anti-wear and detergent films compete for the same space on metal surfaces and that you sacrifice wear protection with too much 'cleaning power', but HDEOs seem to do a good job with wear protection on turbo diesels. In summary I guess I'm suggesting that dino PCMOs in general haven't prevented deposits over longer intervals as well as they could have.