quote:
Originally posted by JohnBrowning:
Use progressively heavier oils in it until it stops. I am betting that 10W30 or 15W50 M1 would reduce this or solve it. You did check the pcv and EGR circuits for proper functioning?
I had beem using 10W30 Mobil 1 until winter. Mazda engines are famous for HLA noise I know, but there was extended HLA noise on cold starts with the 10W30. I switched to 5W30 and no HLA noise, even on cold startup. It used the same amount of oil even with the 10W30.
I haven't checked the EGR yet, but I pulled the valve cover and resealed the PCV baffles in the cover. The Miata's 1.8L has three baffles in the cover sealed with RTV. It has a new OEM Mazda PCV valve.
I plan to pull the intake manifold to clean it, as they have a reputation for carbon build-up jamming the EGR valve open and build-up from the PCV feed that can set a MIL if left too long. I cleaned the throttle body and got a good bit of gunk out of it.
quote:
Originally posted by Robbie Alexander:
Does it burn oil only on these NIGHT trips? Is that what youre saying?
I added that detail because in Texas, the night speed limit can be lower than the daytime limit. For example, I take I-45 to Houston. Daytime limit is 70MPH, nighttime limit is 65MPH. I don't think it being day/night has anything to do with it.
quote:
Since you just got it, and it seems dry, may it be probable that you are using a better oil than the other owner, and it is cleaning and being used up by burining and pulling dirt from the engine?... if a better oil cleans the ring area, that can increase consumption, sometimes for a long while or forever...
These were my thoughts as well. I pulled off a Pennzoil filter when I got the car, and the only place I've seen use those filters were the quick lube (especially Jiffy Lube) places. I've already put 10,000 miles on it (currently at 137,000 miles, got it with 124,000) but will keep an eye on it. I've also been debating about trying Auto-RX.
quote:
Originally posted by Drew99GT:
Sometime adding the fuel filter inline with the PCV valve will increase vacuum substantially through the PCV line, which will suck more oil through the PCV especially when there is less vacuum in the intake manifold and the filter is all soked up with oil. Or, I guess it could completely clog perhaps and not allow proper PCV funcioning, but the fresh air side would then draw vacuum, a lot of vacuum when the engine is idling etc. or decelerating, when the PCV normally closes. That would suck up a lot of oil vapor. These are all guesses though
I had not of heard this. Its something I generally do because oil vapor lowers fuel octane, and as I said above the Mazda 1.8L in the Miata dusts the intake with oil vapor gumming up the throttle body and cause eventually set a MIL. Periodic removal and cleaning of the intake is the usual cure.
Thanks for all the suggestions/ideas. The car runs great so I'm not too worried about it, and I buy the 5-quart jugs of Mobil 1 so the extra usage is covered between changes. I know that higher mileage engines may exhibit behavior like this, I just got spoiled by my '97 Pathfinder's engine using no oil between 5,000 mile changes with 126,000 miles on it.
I also realize that the PCV setup in four-cylinder engines and/or high-revving engines tend to use oil more.