I've been using synthetic oil for the past 20000 miles. I've heard people say it was okay and I've heard people say that it was bad. What do you "Rotorheads" think. Should I go back to regular oil. Would it be okay to go back after using synthetic for a while. Thanks.

 

The bottom line is NO. Don't use it. The RX7 is unique in many ways compared to a conventional piston engine. Contact Speed Nation for their advice if you want a real expert. The thing with synthetic is that it corrodes the apex seals and that will lead to loss of compression within the rotor chamber. Then you are looking at a rebuild because you used a more expensive lubricant. The system was made to run on oil. Stick with the proper grade and keep the oil level up and you will be fine. I had over 200 kms on my last 7 before it was written off. The compression was still good using regular oil. Besides if you travel fyou will always have to make sure you have synthetic.

 

The main problem with Synthetic oils in a rotary is the fact that the rotarys inject a small amount of oil into the comustion chamber to lubricate the seals. Problem is that Synthetics don't burn as cleanly as conventional oils. The oil of choice is Castrol GTX (non synthetic). It does a good job of lubricating the engine but burns clean. For more info come to the 1st gen forum and ask there, or do a search for "synthetic oil" there have been some good posts on the subject already.

 

According to other postings, there are benefits to premixing synthetic oil with the gas. Is this any different on a 1st gen?

Does that mean that Synthetic OK for premix and no good for engine oil?

Thanks

 

Yes you can run sythetics however It needs to be Rotary synthetic
this stuff can be imported from Japan in 1gal. containers its formulated not to leave residue/carbon build up. However its not cheep but if you want to run it that bad youll pay.

Note: RE-Amemeya (did i spell that correct?) has his own line of
synthetic fluids that can be purchased from Rotary tuner
shops. Or you can have Corksport get it for you.

Note 2: When odering anything from Japan you best have
some (patiants?) conserning shipping times...

 

Regular engine oil doesn't mix especially well with gas. The probably ment a synthetic pre-mix oil. They're meant for high performance motors in jet-skis and snowmobiles, but work in rotaries too.

If you REALLY want a REALLY good pre-mix oil to add to your gas, go look for Marvel Mystery Oil (MMO). If you want more info on why MMO, search for posts about it.

 

Let me rephrase the question.


I know that synthetics (or at least most of them) are a no no when used as an engine oil. The reason is due to damage to the apex seals. fine.

Question:
Does a premix synthetic oil (in the gas) or MMO ruin the apex seals just the same?

Thanks

 

No.

Synthetic engine oils are bad because they cause carbon build-up. Pre-mix oils are DESIGNED to be burned, and therefore burn cleanly (i.e. no carbon build-up)

 

This is an interesting topic. Seems like Mazda recommended against Synthetic at some time (do not see this in my '82 owners manual). When? Did this happen for series 1, 2, and 3?

I'm using Mobil 1 because I want its superior cold weather performance (higher cranking speed). Figure as I'm driving it through the winter I need every advantage I can get (installing electric fan so it warms up quicker, and a HOT! air intake to prevent icing (dellortos)) so the engine always starts and runs without stalling.

Synthetics cause deposits?
This concerns me so I reseached several SAE (Society of Automotive Engineers) papers to determine if this is a problem. I found 3 or 4 papers written in the mid to late 70's which investigated this problem. 2 of the were written by engineers at oil companies the others by auto companies (GM was one). The most interesting paper separated the sump oil from the metering pump oil and tested the effect of different oils on the deposits built up on the combustion chamber. At least one oil was a synthetic and they found this to cause the least deposits.

I don't think this is conclusive as the oils tested then would be very different to the oils on the market now. But it shows that it was a concern when many auto companies considered the wankel to be a replacement for the reciprocating engine due to low NOx emmisions.

There are also many more recent papers concerning the effect of oils on combustion chamber deposits in reciprocating engines. But am not sure how relevant that is to the roatary. Those papers don't show an increase in deposits due to synthetics.

The best thing would be to run separate oils in the 2 systems. These oils would be specifically designed for each sytem and not a compromise.

For now I'll stick to synthetic

 

Synthetic oil burns so cleanly and compeltely in the engine that it does not leave anything on the apex seals and housings for lubrication. So Synthetic is not really recommended for rotaries.

On my 12A race motor, the oil metering pump has been removed. I pre-mix 2cycle oil at a 100:1 ratio into the gas. This provides good lubrication. I run synthetic oil in the motor because I regularly see oil temps of 250 degrees on the race track. In a street car, you never get that high unless something is really wrong.

For cold weather (below 40 degrees F) on a street driven rotary,
run a good 5w30 non-synthetic oil and let the oil warm up before
you rev over 3000rpm.

-Darren