From OP: Re Previous Oil Question

1. the notion that synthetic and regular oil can't be mixed is completely false. you "dilute" the benefits of "pure", but they're perfectly compatible with each other.
2. there's not that much difference between the two these days. most refiners have to go down the "synthetic" road to get to modern oil viscosity, so what they call it is debatable.
3. actually, most "synthetic" these days is simply a highly refined [isomerised] conventional oil. so what you're really paying for is the quality of the additive package, which can vary greatly in quality.
4. if you want a "true" synthetic oil, go for some of the ester-based options like motul or red line.

Bob wrote in news:l0fdin$ban$ snipped-for-privacy@dont-email.me:

No it's not. The two are perfectly compatible.

"Synthetic blend" IS a mix of synthetic and mineral oil. You can mix-and-match all you want.

There is mineral oil in the "blend" stuff.

All gasoline automobiles require specific viscosities and API ratings. Provided those two criteria are met, it is immaterial whether the oil is mineral or synthetic, or a blend of the two.

Yes, and you can mix regular dino squeezins with full synthetic too although oil mfgrs. will tell you not to.

Well, typically a true synthetic has better viscosity stability over a wide temperature range than conventional, and also better resistance to coking at high temperatures. So a synthetic blend will have some of the same advantages, but not as much as a full synthetic.

Depends on the car. Most European cars now do require a full synthetic and not just "any" synthetic but one meeting a specific manufacturer spec, and this has been true for over a decade now. So you have to read the manual and see what that spec is (e.g. BMW LL-01 or LL-04, VW

502.00, etc.) and make sure that the oil you use meets that specification. Usually Mobil 1 European Formula or German Castrol (sold as "Castrol Edge" now I believe") meets most of those specs, but check to make sure. In the case of BMW at least they have started to make dealer pricing competitive on items like oil, brake pads, etc. so if you have a dealership nearby it may actually be easier to just buy from the dealership rather than trying to find a parts store that carries suitable oil, contrary to what you may have been conditioned to expect from years of overpriced dealer items.

GM has released their own specifications for motor oil recently called "Dexos 1" and "Dexos 2" and they don't necessarily require synthetic, but you have to read the label. The example I'm familiar with is Valvoline, the regular old Valvoline does not meet Dexos 1 but most of their other oils do (e.g. Maxlife, which isn't a synthetic.) I'm pretty sure that at least in Valvoline world the only oil meeting Dexos 2 spec is going to be a full synthetic.

I don't think that Ford specs require synthetic (yet) - I know Chrysler just released a new spec for the 2013 MY and are recommending that oils meeting that spec be used retroactively for all Chrysler produced engines ever made, but I'm not familiar with what oils meet that spec.

nate

Nate Nagel wrote in news: snipped-for-privacy@news4.newsguy.com:

Forgot about that.

The REAL answer to the OP's question is to RTFM: If your engine /requires/ full-synthetic, it will say so in there. If it does /not/ require full synthetic, then you can put anything in there in any combination you wish, provided the viscosity and the API ratings are correct. The manual may give an oil-change interval, and it may also say that the interval is only valid if a certain specific type of oil is used.

Those oddball Euro specs are primarily meant to operate with the extended change-intervals that those Euro vehicles have. Extended change-intervals are not compatible with non-synthetic oils.

I seem to remember Mercedes recently having to pay out a large sum of money to settle litigation that resulted from just his issue. Apparently some dealers were using oil that did not meet the correct MB specs, but people were following the oil-change schedule as though the oil was MB-compliant. Sludge was the result.

Right - on the face of it you think they're being jerks for mandating that you use $5/quart oil, but then again they are willing to warrant a turbocharged engine for 14-15K mile OCIs, at least up until the factory warranty runs out. So they must have faith in the oil.

I forgot to mention in my previous post, this is just my personal opinion, but in any turbocharged engine I would use full synthetic as a matter of course whether the manufacturer recommends it or not. The turbo bearings get way hotter than any internal part of the engine, and they heat soak when you shut the engine off. Coke in turbo bearings = bad. Additionally, in any engine with any kind of variable valve timing scheme (VTEC, VANOS, etc.) I would also consider running a full synthetic, just to keep the inside of the engine spankin' clean, as at least VANOS solenoids are known to get sticky requiring a decent amount of labor to get to them, clean, reassemble.

Of course then again I'm running either Rotella or Delo full synthetic in a Jeep 4.0 which is about as understressed an engine as you're going to find, but still.

VW had an issue with that on the 1.8T engines as well about a decade ago, and I always wondered if that was not the cause as well (dealership oil changes done under "free services" being done with bulk 10W30 out of the big tank)

nate

I would not bother on something such as a Honda Civic with VTEC to use synthetic - the rest of the car will be worn out before you need to open up the engine.

i would - i've seen those things badly sludged up, including the vtec control solenoid. regardless of other alleged benefits, the one thing you can say for most "synthetics" is that they have good detergent/additive packages, and minimize the impact of this kind of abuse.

Your own or one with unknown history? Mine have never had enough combustion "blow-by" to even turn regular oil dark with 5,000 mile oil change intervals, and no noticeable compression loss after 160,000 miles of being run hard (at which time road salt corrosion had taken its toll on the body and undercarriage).

junkyard kalifornistan civics. sure, they may have been 1-miles commuters, but a good synthetic is highly sludge resistant, even in that regime.

i would also say that cleanliness is essential for good oil consumption too. the motor i currently have in my civic used to burn oil like crazy. but, on the theory that clean piston rings are free to move and thus seal properly, i've been running synthetic/rotella and have seen oil consumption steadily drop. now it's down to ~1 quart in 7k miles. not perfect, but a lot better than it was!

If my previous or current Civics ever used any oil, it was so little that it could not be seen by the relatively crude measurement of looking at a dipstick.

Rotella is damn near magical for older engines that like xW40 oil... I wouldn't run anything else. You could eat off the top of the head casting in my Jeep... I know, as I replaced the valve cover gasket last year. Damn thing looked like new under there. Gave me that warm fuzzy feeling deep down inside. I'm running a CM (formerly Canton/Mecca) oil filter on it for extra insurance, just 'cause I'm a geek, but I bet that simply Rotella (dino or synth, doesn't matter) and regular oil/filter changes would make the thing last longer than the body.

nate

Well, your bet supports my position. Any car or truck I have will suffer from so much under-body rust after 15+ years that it will not be worth repairing, so why worry about the engine? (My 1994 Civic Si, before being totaled out in a minor accident that left it drivable, would have required a cutting torch and more than it was worth in replacement parts to do a suspension alignment.)

The couple of vehicles I do plan to keep long term get synthetic oil, but motorcycle specific since they run wet clutches, and putting something like Rotella T6 in would create clutch slippage.

Newer vehicles tend to have better rustproofing... aforementioned Heep is already 15 years old :) I've only had to repair one small rust spot hidden under some plastic fender flare/trim, and have in my ownership deliberatel y removed and reinstalled some underbody fasteners for the express purpose of putting anti-seize on the threads while I still could.

My cousin (who I bought this from) has a son who just started kindergarten this year. He is very much like I was at his age and is nuts about mechani cal stuff, especially stuff that's old, shiny, and red :) He thinks that h e's going to get to drive the Heep when he is old enough, and it might actu ally be possible - my dad is still driving our grandfather's old Chevy pick up truck, we're just that kind of family. (I just wish we'd kept some othe r stuff, like the flat fender CJ that the pickup truck replaced, etc.)

s already 15 years old :) I've only had to repair one small rust spot hidd en under some plastic fender flare/trim, and have in my ownership deliberat ely removed and reinstalled some underbody fasteners for the express purpos e of putting anti-seize on the threads while I still could.

n this year. He is very much like I was at his age and is nuts about mecha nical stuff, especially stuff that's old, shiny, and red :) He thinks that he's going to get to drive the Heep when he is old enough, and it might ac tually be possible - my dad is still driving our grandfather's old Chevy pi ckup truck, we're just that kind of family. (I just wish we'd kept some ot her stuff, like the flat fender CJ that the pickup truck replaced, etc.)

Forgot to mention - I did an oil change in a friend's motorcycle a while ba ck and I researched online to make sure I used the right products, because while I know a bit about cars, motorcycles really aren't my forte. Bike wa s a Suzuki something or other (600cc 2-cyl, "standard" bike) and the online consensus was that Rotella synthetic was the right stuff to use, so I did. Dunno if that was wrong or right, but a test ride afterwards was entirely underwhelming - it rode exactly like it did before messing with it.

nate

Maybe.

The problem is that oils that are sold as "synthetic" in the US are often just ordinary paraffin oils which have been very tightly refined to a narrow range of molecular weights, rather than esters or some other synthetic molecule.

Most of these oils cannot be sold as synthetic in Europe, even though they can be sold as synthetic in the US.

A few years ago, the Castrol Syntec 5W-40 formulation was a synthetic ester oil, while the other Syntec oils were all highly refined paraffins.

What does this mean? Nobody really knows, because you don't have a good idea about what you're actually buying when you buy a synthetic oil or a blend because the actual formulations are all proprietary. You only know it meets the minimum API standards... if it exceeds it, you have no idea how much it exceeds it because there is no established testing standard.

Maybe you care about breakdown under shear conditions. Maybe you care about how well it keeps a film under high pressure. Maybe you care it doesn't coke up in a hot turbocharger when it's shut down. Maybe you only care about how much blow-by it can keep in solution. Depending on your engine, you may care about very different characteristics.

But, since you don't really know anything about any of those characteristics unless you measure them yourself. So you pays your money and you takes your chance.

--scott

SOME of those Euro specs are also useful if you want to keep a lot of blow-by gunk in solution. I change the oil on the 2002 every 3,000 miles, but when I do it's pretty nasty. After 480,000 miles it might be time for new rings.

--scott

correct, but not just weights, formation too. a branched chain can have the same weight as a straight chain, but different viscosity/lube characteristics.

true.

the /public/ don't know. the people that sell/make the stuff know.

fact is, the public are probably the /only/ people that don't know because everybody in the industry knows - they're just not telling in case they can't sell their $3-per gallon stuff for $20 per gallon any more.

in indonesia, there is a large "g.t.l." facility that turns natural gas into oil. that oil is then sold locally as diesel fuel. and profitably. that facility also makes oil that gets tanked and shipped to the u.s and used as base for "synthetic" motor oils since it is highly isomeric - and technically, it is indeed "synthesized" in that a polymerization process is used in its creation. so think about that - local diesel fuel vs. your high end lubricant, and the price differences thereof...

right. but you can get what you pay for if you know where to look. the subject at the public level is highly obfuscated by more opinions than there are people, but the correct information is out there if you want to spend the time looking.

Sure it was 600cc? I would expect most V-2 standard Zooks to be 650cc (SV650, Wee-Strom, Gladius, SFV650) while a 600cc would usually be a I-4 sport-bike (GSX-R, Katana).

While it is not guaranteed that a wet clutch will slip with a non-specified oil with "friction reducers", it makes it more likely, particularly at large throttle openings in the higher gears.

You can have your used oil analyzed for wear products to see how effectively it is working.