So I have a 90 with 134k 1.6 and an older 2554. It has been turboed for 30k but it did not have the oil restrictor. I added one 5k ago and it has not impoved oil usage. So the car now uses oil about 1/2-3/4 a tank. It does not leave a lot of oil on the floor and it smokes on cold day right after it starts and a little black smoke at full throttle but really thats about it. It does leave a black mark around the exhaust and when i pulled the cat it had been turned black with oil.

So here is the 100 dollar question. Is it the turbo or the valve seals. I have a 04 1.8 swap planned but have not got all the parts yet. I need a new turbo for the new 1.8 so I am thinking of buying a 2560 and throwing it on the 1.6 while I get the rest of the parts together for the swap.

So will swapping the turbo fix most of my oil usage?

 

Oh and is the 2560 a good choice for a non built 1.8 vvt 04 engine.

 

find out where it's going first.

if it's your rings, obviously changing the turbo wont help.

 

Turbo rings or piston rings?

You can cold-start the car, let it idle up to temp, then turn it off, remove the turbo, and see if there is crusty-oil burnt flakiness in the manifold and possibly the turbine, or if it's all behind the heat-sheild. This will tell you if it's from the engine or the turbonator.

 

Or check the intake piping, the compressor blades, and charge piping for oil first most.

that will help pinpoint if it's coming from the crankcase due to blow-by, or the turbo from over-oiling.

 

The cold side is almost oil free and I dont rember the turbo manifold being oily when I changed the turbo gasket but I did not honestly check. Dhoo i should have checked dam.

 

https://www.miataturbo.net/engine-performance-56/compression-leakdown-results-what-now-64069/
Do what I did in this thread and report back with the numbers on both compression and leakdown.
That thread should be made a sticky...BTW

 

I have done a compression test and it was 179 185 185 170 but it was right after it had been running so if I had oil ring failure it would have already had oil in the piston. Although I have never noticed oil on my spark plug.