Subject: 1988 RX-7 with 117,000
From: paul lamar
Date: 7/23/2016, 8:05 AM
To: A10-Me-Earthlink



Paul I have followed you for many years and I ran into the above car
last week and bought it. Please tell me what 2 cycle oil to mix with
the gas and what to do to keep it running.

Peter  Duffecy

You lucky dog. Most that age have over 300,000 miles.

Use Walmart 2 cycle oil offered in gallon cans.

It has an injection pump so you don't need to mix oil with the fuel
IF the nylon lines are still OK.  A BIG IF. At that age they are
brittle and could crack at any moment. I would replace them with
steel brake line but that might take a lathe.

These cheap plastic lines are critical to the life of the apex
seals, and engine for that matter, if you are not mixing 2 cycle oil
with the fuel.

Paul Lamar

Should I assume that the lines are bad and mix oil till I can be
sure. How can you check these and I do have a lathe available to me.
Peter Duffecy

Yes by all means that is the safest way to do it.

However they could be cracked and there could be some engine damage.
The engine may still run. It is a good idea to check the oil lines
and the compression.

Nylon oil line failure is the main cause of Rotary engine failure.
If it gets apex seal oil it will last at least to 300,000 miles and
probably a lot more.

The apex seal wears very roughly  at the rate of .001" per hundred
hours at full throttle. The seals probably can tolerate .030" total
wear. That would be 3000 hours. If you put Iannetti silicon nitride
seals in it you are looking at 20,000 hours :-)

Paul Lamar

Paul

by chance is there any data or estimates on the wear when using
Iannetti SiN seals. I assume they are much more tolerant to
conditions of reduced (or zero) apex oil feed. With the SiN seals,
most of the wear will probably be on the housing liner rather than
on the seals themselves

Regards Simon S

Other than the 20,000 hour estimate I have no data.
A line in the  housing is  only in contact with the seal for a short time so
most of the wear would be on the seal. The Mazda housing liner is hardened
steel chrome plated and will last a long time if you keep the grit
out of it.

Did you get any money yet to build and test a  TC rotary :-)
I'll loan you my TC 3 rotor. No problem loading it
into my new stealth motor home.

Paul Lamar

Wouldn't an 88 be a 13B?

Joe Rogi

My mistake. It has been a long time :-)

According to the book RX7 by Brian Long
page 190 the second gen (13B) started in 1985.
They still sold first gen's as 1985 models.

So 1988 was well into the 2nd gen 13B's.

802,522 total  RX7's were sold.

This of course does not include R100's, RX2's, RX3's, RX4's, Cosmo's
and pick up trucks. Not to forget the RX8. I had an RX2, and RX4 station
wagon, a 13B Cosmo, 2 first gen RX7's and now have an RX8.

Rumors have it over 2 million rotaries were sold.

I will buy an RX9 when it comes out next year or maybe I will wait
a year to be sure the wacko environmentalist, AKA Democrats
don't screw it up. Mazda got suckered in and cut back the apex  oil
supply too much on the early RX8 engines. Consequently many  early
RX8 engine failed. The obvious thing to do is make an optional apex
seal two cycle oil tank available.  Most diesels that don't cheat (VW)
require a pig piss tank. The rotary engine injects and burns apex oil out of the oil pan regardless. You might as well buy two cycle oil and then save the oil in the oil
pan.

Mazda also refuses to recommend synthetic oil as well.I suspect that
burning synthetic oil produces less hydrocarbon
emissions. My 12 year old 2004 RX8 goes through the draconian California
smog test with flying colors despite the fact that I add approximately
1/2 ounce of synthetic  two cycle oil for every gallon of fuel I put in the tank.

Paul Lamar

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