Eldragon0

I'm back!!!!!! Not that I ever left. With another hopeful prospective :2006 MAZDA RX-8 52k miles with Summer & Winter tires included
Great condition, beautiful car, (haven't test driven it) But have been informed that it runs smooth as silk. spent a good 20 mins on the phone with the guy explaining to him was a compression test was....following my request for one. From there I inquired what kind of records he had. He stated he has a folder of about 100 records from checkups to oil changes, every one he's ever had (every 2500-3000 miles ). So, so far so good. He still uses it and said he loves it, and want's to sell it to some one he thinks will take good care of it, so he's at least somewhat passionate about it.
B
U
T
BUT
He said he's NEVER put oil in between oil changes...I know we burn oil like we mean it. I've come to understand, roughly a quart ever 1500 miles depending on how hard we drive her. That means between every oil change he's roughly 1-2 quarts under. I don't know what that can do to an engine, but I don't ever want to find out first hand. Does anyone know if that would cause carbon buildup or loss of compression faster ( I'm assuming it would)

Carbon8

iTrader: (4)

Looks clean, other than that the price is high and I would not want an 8 that ever saw a winter. Get comp numbers and then its up to you.

Eldragon0

Well sorry to say :P But it's going to be my DD, and it'll be loved by many Minnesota winters.
I'm more worried about the effects running 2 quarts low on oil can have though. He's been doing it forever... So if the compression comes back good, does that mean it did no damage? Or is there possibly damage that could be cause by this that a compression test wouldn't show?

turboguy327

iTrader: (1)

I have a 07 with 28k miles and I have never had to add any oil between changes. It uses almost a quart by the time a change is due. I dont drive it real hard all the time but I get the revs up high a couple times a trip. Im running 5-30 castrol if that makes a difference. I called a local dealer concerned about lack of oil consumption and they said thats normal and its nothing to worry about. Should I be worried?? I just ordered an accessport so I can turn the oiling up a bit if I need.

monchie

Don't worry about it, its normal...

Eldragon0

QUOTE from RIWWP : The oil burning story:
The RX-8 burns oil intentionally. The only way to to lubricate the seals inside the combustion chamber is to inject oil (or have oil in the fuel, called premix). This oil then gets burned under combustion, so it has to keep oiling, and oil keeps burning. On average, you should see about a quart of oil burned every 1,000 miles. If you aren't burning anywhere close to this, something is wrong.


.....I'd really like some clarification on this I can't seem to find any information on the ill effects of not filling your oil.
From what I've gathered, as long as the oil light doesn't come on he's not dangerously low. But constantly driving on that line can't be good for the engine.

RIWWP

iTrader: (2)

The oil is 4 stroke crankcase oil. It's primary purpose is to lubricate the e-shaft bearings. 2 stroke oil is better for injection, but can not possibly provide protection for the bearings. Rather than increasing the burden on the consumer to maintain 2 different oil types and sources, Mazda made the simpler choice to inject crankcase oil.

Running the oil low / out isn't good for the seals, but it's not immediately harmful. However, it is terminally destructive to the bearings. Just like running a piston engine out of oil.

The ill effect of not filling your oil is running out and melting your bearings until the engine seizes.

Eldragon0

Thank you RIWWP . Now if I am comprehending this correctly ( very good chance I'm not) The bearings would be terminally damaged by this if done in excess. However the engine (bearings aside) would be fine. So I won't see any issue in the compression numbers persay. But would that affect something like the RPM's during the compression test, due to the bearings being harmed?

RIWWP

iTrader: (2)

I have no idea how to answer that. "The engine" is the entirety of the parts. "The engine" is damaged covers anything from apex seal failure, side seal failure, a hole in the housing, housing crack, iron cracks, e-shaft bearings damaged/melted, stationary gear teeth damaged, etc etc etc

What it seems like you are asking is something skin to:
"If I crack one of the four pistons in my engine, is the engine ok?"

Eldragon0

... Fair enough. I'll try to re-word it. If damage was caused by running low on oil. Would it reflect on a compression test. Or is it one of those situations where it will run fine until it just gives out?

RIWWP

iTrader: (2)

It's tough to say.

One theory is that bearing damage would 'unbalance' the rotation of the rotors, resulting in unbalanced apex seal contact and greatly accelerated wear.

If the engine can still run, this is the most likely scenario.

Several past occurrences of running out of oil as reported on here has resulted in the engine seizing up completely, at which point no compression test can be performed at all as a compression test requires engine rotation.

We really don't have much to go on for anything in between.

Eldragon0

Again, thank you for the clarification. I did speak with the owner, and it's currently his DD as well, he said she runs great, and he does take care of it well. So if I can get a good compression test, and talk him down on the price a bit. I may go with this one