I was on miata.net and came across this article: http://neptune.spacebears.com/cars/stories/mobil1.html

It seems that as the Mobil 1 aged, wear in the engine actually decreased. The oil was regularly topped off though and it seems that the author is speculating whether the top offs were what kept the oil going for so long. I wonder what this means from a RX-8 perspective, especially for frequent oil changers such as myself considering though we may change in 3000 miles or shorter intervals, we're only changing about 60% at any one time. Comments?

 

The fact that the rotary consumes oil means we are constantly topping off right

 

I've read in a couple threads that Mobil 1 is actually one of the few synthetics proven to be bad in a rotary. Something about it's burn qualities and ash it leaves behind? I've always thought it was a pretty decent oil for other engines, though.

 

A lot of RX-7 owners have used Mobile 1... Including myself... But recently I decided to use good ole mineral oil as I change my oil on my 7 every 1.5k miles and it was little too much (cost wise).

But using Mobile 1 for past 3+ years, I do think it does not harm rotary engines..

 

Back to the original point - about the longevity of synthetic oil. When they first came out, one of the highly touted features was long life. I think one spin was that you'd never change oil again, other than what was replaced when changing oil filters, and maybe what was normally consumed.

Long life violated automakers required maintenance schedules, so that position went away. But the capability didn't.

Ken

 

Violated maintenance schedules, and cost dealerships $$$ - so the longevity is still there, but we're forced to ignore it in order to keep the warranty.

Threads here, and a few people worth listening to - but it was a Renesis specific potential issue. Not sure if anything conclusive was given - just speculation.

 

There are a couple of TSBs in the oil threads, one from Mazda Australia and one from Mazda Netherlands (I think) that show carbon-clogged ports that they attribute to synthetics.

I thought the Mobil 1 specific issue was ancient history - had to do with additives in the original formulation together with side seal material Mazda used way back.

IMHO, anyone really interested in the topic should read all of the relevant threads here before reaching any conclusions/opinions. Finding all of that discussion would make a pleasant evening's entertainment.

Ken

 

fixed.

 

No, not proven. The result of a discussion with a Mazda elder, who apparently "doesn't like" Mobil 1. For what reason, and whether or not that was due to experience with Mobil1 from the '70's, '80's, 90's or 2000's, I don't believe was ever made clear. The discussion was difficult due to language problems, iirc.

 

Mobil 1 is no longer a Group IV true synthetic. It is now a Group III hydro-cracked petroleum base oil.

 

That's a huge debate. BITOG often seems more confusing than informative. I know Royal Purple, a favorite here, often isn't looked upon very favorably by some members there. At least that's been the case for the last year when some users have had used oil analysis of Royal Purple that hasn't turned out to be stellar.

 

The guys on BITOG may hate to hear this, but as with most other forums, the general population there doesn't know a damn thing about oil. A few of them do though. Even though it is an oil based forum, I donb't really trust al of the information over there. They put too much faith in used oil analysis results since they don't really know what they are looking at. Take everything over there with a grain of salt. The one oil that I do agree with those guys on is Havoline conventional oil. It's good stuff and my favorite conventional oil.

 

I thought you liked Castrol GTX the best. The one true thing about internet forums is that it's often the guy who shouts the most/loudest that gets his word believed, not the one with actual knowledge.

 

If you want a "true" synthetic you need to go with something ester based like Redline or Motul.

Mobil 1, Royal Purple, Castrol, Pennzoil, etc... are just giving relative amounts of synthetic oil, which could be PAO, Ester, or combo of both, MIXED with dino oil at different quantities which would depend on the company. A certain amount of "synthetic" oil is allowed to have dino oil mixed in.

You can't totally trust the word "synthetic" thanks to Castrol and their hydro-cracking scheme to get dino reclassified as synthetic in the court battles with Mobil.