RE: Oil Consumption

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The rotary engine burns a small amount of sump oil as a part of the engines normal function.

This oil comes from the sump, and is injected directly into the combustion chambers to help lubricate the apex seals, which also helps with compression.

Oil consumption varies from RX to RX depending on how old the engine is, how it is driven etc.

A general rule is around 1 liter per 1000 miles. But if you are doing track days, it is possible to use 2-3 liters for a day session.

Always keep the oil level near full, again if you corner hard and the oil is low it can potentially move away from the oil pick-up in extreme cases.

Oil Consumption

The RX-7's rotary engine injects oil into the combustion chamber as a part of normal operation, for lubrication purposes. So some consumption is normal. Some people have noticed a gasoline smell in the oil when they changed it. No official explanation, but Kevin speculated that it was caused as a result of the higher temps in the rotary. Carl conducted a poll on it, results below. --Steve

Date: Sun, 09 Nov 97 12:34:00 EST From: "Houseman, Carl W. x1323"

There were a total of 15 responses which answered at least the question about how strong the gas smell was and what oil consumption was. I feel these may be the two most important questions.

Granted, the smell business is very subjective. But I find the following meaningful correlations in the data:

1. Everyone with "no oil usage" or "level increases" reported either a "noticeable" or "strong" gasoline smell in the oil. (8 responses)

2. Everyone with "strong" gasoline smell reported "no oil usage" or "level increases". (3 responses)

3. Everyone with "slight" gasoline smell reported measurable oil consumption ranging from 1500 to 9000 miles per quart.(3 responses).

There was exactly one exception report of "noticeable" gasoline smell with relatively high oil consumption (1000 miles/quart).

There were only two reports of strange noises at startup which weren't easily explained (and one of pffft at shutdown).

There were only 8 responses to the "long" survey, which wasn't enough data to come up with a correlation between gasoline smell/oil consumption with driving style, oil weight, or trip length.

Question of the day: What is it about some of these 3rd gens that they don't use oil? Is it really gasoline dilution, or something else?

Here's the survey questions again in case you missed them.

1. Classify the smell of gasoline on your dipstick - none/slight, noticeable, or strong. 2. What is your oil consumption? Miles per quart, none, or level increases? 3. What kind of oil do you use - weight especially - brand also. 4. Miles since your last oil change? 5. What kind of driving - short, medium, or long trips? 6. What driving style? Easy, Hard, Mix of easy/hard, Track? 7. Year and mileage on your car (optional)

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Date: Mon, 10 Nov 97 11:39:00 EST From: "Houseman, Carl W. x1323"

Update:

Since posting my survey results I've gotten about 10 more responses. Some of those run counter to the previous trend (it figures - post a hypothesis and people will to disprove it). I'll re-summarize when I reach about 30 total responses, or next weekend, whichever is later.

Also in the same counter-to-previous-trend feeling, this morning I finally did a _comparison_ sniff test. I have a 92 Mazda B2600 pickup and it, too, NEVER uses any oil. I figured it's just a very tight engine. Anyway both were run yesterday and both were stone cold this morning I did the sniff test and they smelled EXACTLY THE SAME. I would have only characterized the smell as "slight" this morning. I'll do a warm-engine sniff comparison next. Stay tuned.

And if all this wasn't bad enough, I hesitate to point out that if winter fuel formulations have hit the gas pump (I suspect they have), cold weather fuel is more volatile (vaporous) than warm weather fuel.

What a pain. I need to ask my Mazda mechanic (a good one) what he thinks about the situation.

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