ester oils and engine durability

Why don't you want an ester base?

And what does "durability" mean? It depends a lot on the service. You can get an oil which is very immune to shear and breakdown, but it will still saturate with blowby detritus. Because there are so many different failure modes for the oil, you need an oil which will address all of them, but most notably the ones which are most an issue for your engine.

Is your goal for your engine to last as long as possible or do you want to extend oil changes as long as possible? That is, do you care about engine or oil durability?

If your goal is for your engine to last as long as possible I recommend doing frequent oil changes no matter what oil you use.

The MSDS will tell you roughly what sort of base is used. That's not a lot of detail, though.

--scott

he likely also needs to supplement the oil with zddp. oil specs have changed dramatically over the last few years, and zddp level reduction is killing a lot of older motors with non-roller cams.

most msds's go out of their way to obfuscate contents, especially base oils. it makes mockery of the whole msds system if you can simply label something "proprietary" and then get to not declare what it contains. particularly when you consider that anyone with a lab can do analysis so the only people being deceived by secrecy are the public, not business rivals.

switching back and forth between synthetic and mineral is ok for a car with a very old engine design (60s) or I'd better keep running full synthetic in it?

doing 6k oil change intervals for synthetic 5w-40 now on my A4. Same for the fiat 124 beater

why would you keep switching? makes no sense.

the audi should have better combustion and lower blow-by product, so it should need less frequent changes. and the whole point of a synthetic is that you can extend the change interval. follow what it says in the manual - that's usually quite conservative.

I second that. I looked up an MSDS for kerosene, expecting it to list nonane, decane, undecane, whatever. It just said "non-aromatic hydrocarbons" > 95% Fricken useless......

No, it's very useful if you want to know what to do about it in a fire or a spill. The MSDS is intended to supply safety information. That is what the S is for.

Now, if you look a little closer, it will list the flash point and some information about vaporization. You can use that information to figure out at least how big the lighter fractions in there are.

The MSDS is not there to aid in reverse-engineering a product, and manufacturers will work hard to avoid putting information in there that could be used for reverse-engineering. But they have to put a certain amount of information in there and some of that can be very useful.

--scott

that's somewhat of a warm and fuzzy you're giving there dude. while some manufacturers do provide helpful information, others go out of their way to obfuscate, particularly when it's a product with a high price but cheap ingredients. calling a base oil "poly alpha olefin" when there's no "poly" and under modern convention, they should be using the word "alkene" for example. and i say again, they're NOT preventing reverse-engineering by anyone with a modern lab.

bottom line, while the msds system started out well intentioned, it's become a perverse travesty in pursuit of blowing smoke up the consumer's ass.

compare:

to save a few pennies: no wallmart with it;s 5qt jar house brand synthetic for $20 around here

Specifically concerning the ester based oil, truth or myth: the ester base oil degrades quicker than synthetic with other bases?

How much of oil properties degradation is controlled by the additives and how much by the oil base

It depends on the conditions and on what other bases you're comparing it with.

If you're driving a 1960s car, the odds are that the oil will become clogged with blow-by products before the base breaks down, so you don't care much about the base breakdown.

The breakdown of the base oil under shear will depend on the oil base. The solvent properties will depend some on the base and some on the additives. The ability to keep constant viscosity with temperature will depend almost entirely on the additives.

Which is an issue depends on the failure that you are encountering which in turn depends on your particular conditions. From my perspective, the advantage of the synthetic oils has to do with better flow characteristics and better protection under high pressures rather than any ability to leave it in the crankcase longer. But then, I am mostly driving older cars where the oil change interval is limited by blowby, and I am tending to change oil a lot more often than needed anyway because I don't mind doing oil changes and I hate doing engine work.

Once I owned a Chrysler Laser, which has a turbocharger which normally fails around 60,000 miles because the oil makes out in the turbocharger and varnishes up. I used synthetic oil in it because the synthetics generally bake out only at much higher temperatures, I changed the oil every 3,000 miles, and I let the car a minute before shutting the engine off. I got 450,000 miles on it and the turbocharger was still fine when I gave up on the fifth transmission rebuild. This is an example of an engine with a different failure mode that puts a different stress on the oil and so the change interval is limited by a different factor.

--scott

I guess I could just as well save the money and use mineral base oil in the fiat based beater then. Maybe add half a quart of full synthetic and call it a day. Will be better and cheaper than half synth that has 50ml of synthetic per liter of mineral if even that.

Ah, so the oil IS routed to the turbo after all. No wonder audi specified synth for the AMB engine then. I guess I'll keep feeding 5w40 full synth to that car then. I wonder how the turbo is coupled to the engine to allow oil flowing in there? And also are there some sealed bearings in the turbine?

The 2nd gear synchronizer(s?) are nearly toast on that car but I'm waiting for a bigger issue to rebuilt the tranny. Learning to rev match until then ;-)

thanks Scott.

spend the money, get oil analysis done, and extend the change interval accordingly. synthetics allow extended change intervals and reduce friction and thus consumption. if you do the math, you'll find they pay for themselves.

complete myth. jet engine lubricants are ester not alkene based /because/ of their superior stability.

define "degradation": you can add anti-oxidants and buffers which help, and viscosity improvers, but it's the base that holds the fort.

the only thing you need to watch out for with esters is oil seal performance, but if you have a vehicle newer than the 70's or not cheapo detroit crap, you shouldn't have much of a problem. and quality oils have seal conditioners in them anyway.

there's no real reason not ti use a synthetic if you're not into recreational too-frequent oil changing. they're much more stable, can handle poor engine management better, and will preserve expensive vintage toys better.

but like all new oils, you need to watch the zddp levels. those have been cut back dramatically in recent years, even in synthetics, and older engines suffer badly from lack of this crucial high pressure lubricant. it's wise to use a supplement on these old engines, whatever oil you use.

if you deal with that right away, you might be able to get away with replacing just the synchro ring. if you wait, you'll screw up the dog teeth on the gear and the lock ring - requiring much more expensive purchases of new ones.

also, the main reason synchros go is that the clutch disk isn't fully floating on the input shaft so there is still some drive when you're trying to shift. examine the clutch plate when you remove the transmission - if wear is not even on both sides, this was definitely your problem.

when you reassemble, make sure the shaft is properly lubed with antiseize where the clutch plate goes. if there isn't one already supplied in any clutch kit you get, get some. some of the oem lubes are synthetic ceramic-based lubes like you can get for brakes, so i'd use one of those.

on the big old trucks, even though they had synchros, that was the /only/ way you could get them to shift. some of the even older truck drivers used to hate them because the prior generation of straight cut synchro-less transmissions were easier to shift if you had the knack.