another newbie question...which oil?
 

Hey Folks,

I want to change the oil in my wifes 1981 RX7 and I 'm not sure what oil I should use. I am a huge believer in synthetic but I pretty sure I read that synthetic oil in a rotary is a big no-no.
What type/viscosity is recommended? The car is in awesome condition but there is 100,000 miles on it so I would like to make the proper choice.

Once again, any help or advice is greatly appreciated and Thank You in advance.
Brian.

since the engine actually Burns Oil,Regular 'Dinosaur" oil is acceptable for your engine.Personally,since I am in Canada,I run a 10w30 in my car.It only sees summer.but if you plan on running it in winter also I would change the Viscosity.and run 5w30.That way the oil would be less thick from cold and allow easier start-up.Don't use a Crappy one dollar bottle oil.Using a Premium grade oil like Castrol Gtx is Good.it won't Breakdown as quickly like the cheaper oil does under heat.Now That Viscosity is What I run,no problems,and I am pretty well driving a Stock running vehicle..Other people will chime in with what they use, and It may change depending on what Mods they have and how they Drive the Car too,and where they drive it.

This car is way too nice to be driven in the winter. I just thought it may require a heavier weight oil because of the revs it is caple of.
Thanks for the quick reply.
Brian.

if you aren't doing any winter driving go with 20w50.

there's been some debate over oils for rotary engines. i personally believe that synthetics are superior in everything an oil has to do. just do a bit of research on engine oils and that will become apparent.

however, i'd recommend you just run a good conventional oil like Castrol GTX. two reasons.
1) your car has most likely been using conventional oil since it was new. it's better not to switch after this long.
2) a Castrol GTX is much cheaper than a Mobil 1 (or whatever). there really is no reason for these cars to be running high grade synthetic. just change your oil on a regular basis (at least every 5k km).

now oil filters is another topic that seems to cause shit around here, so i won't get into that. :)
just buy a good one (Napa Gold are great and easy to get). no Fram!
and change with your oil

If you won't take it out in winter, go to your local crappy tires, and buy any oil container that has the mention 20W50, but not the Motomediocre brand.
This should set you up just fine.
If you're still going to keep it out until the first snowfall, meaning in close to 0 degree temperatures, then go with 10W40.
I'm glad you're taking good care of your FB!

What the last two posters said

Im a big supporter of Mobil 1. But for the RX-7, Castrol GTX all the way. It seems to burn a bit better I think. And for the price, you cant argue, since your literally burning it away.

20w50 Summer, 10w30 Winter.

I've been doing some research lately into Used Oil Analyses and I'm a believer. In particular the flash point tests would be very important in an RX. My old oil used to smell like gas pretty bad at about 3,000 Km and in hindsight I think it might have been diluted with fuel enough that it was burning too easily and also not protecting properly. A properly-interpreted UOA will provide hard data regarding these concerns and I wish I would have known about them 5 years ago.

You can read about them and see what other's have been getting here. http://theoildrop.server101.com/foru...rd=UBB3&page=0
I strongly recommend this guy http://www.dysonanalysis.com/ to do the analysis as he's been doing it a long time and really seems to know his stuff. $50 usd for a test. Well worth it IMO!

FWIW, I blend Castrol 10/30 and Mobil1 20w/50, half and half - partly because of being reluctant to run full synthetic in a (now) 16yr old car that for the vast majority of it's years used regular petroleum oils. From a lot of reading and discussion with rotorheads whose expertise I would trust, synthetic is mainly a concern because not all are created equal - some, like Castrol Syntec, Havoline, and a lot of other popular brands are in fact hydrocracked dino oils, and have the downside of leaving ash deposits when burned, just like carbon buildup in terms of scoring and damaging seals. Others, like Mobil1, Royal Purple and Redline, Motul, Amsoil use PAO or synthetic esters that don't have the same ash problem. Mine's run summer only, and a lot of track use, which is part of why I like the 20w50 synthetic for increased protection in hard-running.

Just for the record, Mobil1 no longer uses a PAO base - there's extensive talk on BITOG about it. Not looking to derail the discussion but just trying to keep everyone up to speed!