horn4858

castrol 10-40extreme cold,20-50 normal temps. they don`t make any better oil.

13BAce

But a small amount of oil is injected into the air/fuel mixture and burned during combustion. Most synthetic oils will leave carbon deposits when they are burned. And that is not a good thing with rotaries.[/quote]

Somebody I know did a test where he put different oils in a spoon and held them over a flame. He said that Mobil 1 burned alot cleaner than the regular oils. I think that Mobil 1 used to leave alot of deposits, but the formula is different now.

Powerpack

There are 2 things to keep in mind here. We have to look at the rotary engine as a 2-stroke engine so the oil is there to lubricate AND to burn after.



Like in 2-stroke engine, if you use an oil with a flash-point that is too low in an engine with a high temperature of combustion chamber, the oil would burn before lubricating and leaving no carbon deposit. If you use a high flash-point oil in low temperature engine, the oil would lubricate and carbonize there instead of burning. So the test in the spoon is valuable in pistons since the higher the flash-point the better the oil resists to high temp degradation. That's the case for synthetic motor oil and the best oil, but in rotaries we have a 2-stroke engine in a 4-stroke so we have to compromise.



Anyway I've been using Castrol GTX for several years now but it's just a personal choice, I've never made test on carbon deposit on my RX7, because it's too complicated to inspect the internal parts but I always did on my 2-stroke engines. As an example, in kart racing, Motul sells oil for 18000rpm and 23000rpm engine at the same price. You would think that the best is the 2nd but in a cooler engine the first one is the best (different flash-points). Those are synthetic oils but formulated for 2-stroke engines.



If rotaries would represent a big part of the market, I'm sure we would see specially formulated oils for them (N/A and turbo). :thumbs-up:

90N/A Rex

Powerpack

It probably costs alot more than standard oil and even synthetic oil since it's a small market. Which oil company is making this product? I know it's written "ITS" on the container but it's probably the company who ordered the formula from an external oil laboratory. BTW, is it synthetic? And is it really a good product or is it a marketing product?

90N/A Rex

That can is $107 from corksport. I know nothing about the oil except it is made from Mazdaspeed and probably bought by them from some oil lab. :whatsthat:

I use Castrol GTX in my 7. :satisfied:

Powerpack

Thanks for this info, that's interesting to know anyway. If the market would grow up towards rotary engines, we should expect to get that kind of oil for a decent price. Until then we just try to choose the more appropriate oil among the others.

rota-re

Money is far better spent using a good mineral based oil and changing it twice as often, than using an oil designed specifically for rotaries anyway....

Powerpack

We're just talking about what would be ideal oil for lubricating and leaving less carbon deposits. Even if you're changing oil everyday it will not change the way it burns. Rotaries are not like other engines when we're talking about lubrication. It's just a matter of choosing which one to use and it doesn't mean we have to pay more.