Moving higher and lower from recommended viscosity

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I'm seeing UOAs with massive fuel dilution and still very acceptable wear metals. 20 and 30 grades turning into 16 grades where the manual calls for 20 or 30 grade, not 0W16.

Other people combating the dilution by using 40 grade oil in car that specs 0W20. No issues.

I have to part my MX-3 out and put the 2.5L 200HP engine into a better condition mx-3 (that I am still on the hunt for). The one that I will eventually find will have a 1.8L V6 130'ish HP engine. It specs 10W30. My thought is (before swapping to the 2.5L engine) to run 50 grade on it because 30 and 40 are widely tried and tested on this engine. And then some 20 grade. And then some 0W16. I'd probably drain the oil, then run desired weight, then drain that and refill after 1000kms or something silly. Just to normalize the viscosity if that makes sense. Would log fuel consumption and note the feel of the engine during tests. Could and should UOA too, to see if there's actually a discernible difference.

Also, I have such a silly oil stash right now, some of which is 10L of 20W50 and 5L of 5W20 so it's a good way to lessen the load in the name of [censored] science.
 
I tried 20W50 in my gf's old 4 cyl Probe (1990 maybe?) many years ago because it burned oil so bad. It REALLY bogged that engine down. I drained it and went back to 10W30 and all was good again.
 
Originally Posted By: FermeLaPorte
I wouldn't go so high. I would try 0w40

This is Australia, 20W50 is always an acceptable grade, it's in the constitution or something.
 
Originally Posted By: SR5
Originally Posted By: FermeLaPorte
I wouldn't go so high. I would try 0w40

This is Australia, 20W50 is always an acceptable grade, it's in the constitution or something.


lol.gif
 
My '94 302ci calls for 10W-30. I investigated viscosity measurements for the high end and decided I would run 10W-40. Big change centipoise-wise in 30vs40. I want the extra cushioning at operating temperature.Oil pressure gauge indicates no change so it must flow unrestricted.
 
Originally Posted By: KL31
My thought is (before swapping to the 2.5L engine) to run 50 grade


You won't hurt the engine, but it will feel a little sluggish.
 
Originally Posted By: aquariuscsm
I tried 20W50 in my gf's old 4 cyl Probe (1990 maybe?) many years ago because it burned oil so bad. It REALLY bogged that engine down. I drained it and went back to 10W30 and all was good again.


When my 1990 Tempo had about 140K I tried one fill with M1 15-50. Bogged my engine down as well. I left in one week and went back to M1 10-30.
 
My rule is if the engine is starting to use or leak oil then switch to the next highest grade. I have a 07 mazda3 that i used 0w20/5w20 for 120k miles then swiched to 5w30/10w30. 180k on it now, no leaks and doesnt burn oil. As soon as i see any sign of burning or leaking i will switch to 5w40/10w40. Been doing this for over 15yrs. Works for me.
On the other side if motor calls for say 5w30 then i wouldnt go a grade lower 5w20 unless you have an oil pressure gauge and know its 100% safe.
 
Originally Posted By: Serge
My rule is if the engine is starting to use or leak oil then switch to the next highest grade. I have a 07 mazda3 that i used 0w20/5w20 for 120k miles then swiched to 5w30/10w30. 180k on it now, no leaks and doesnt burn oil. As soon as i see any sign of burning or leaking i will switch to 5w40/10w40. Been doing this for over 15yrs. Works for me.
On the other side if motor calls for say 5w30 then i wouldnt go a grade lower 5w20 unless you have an oil pressure gauge and know its 100% safe.

The engine in my 2007 Ford Fusion is the 2.3. Probably the same engine that you have in your Mazda. I now have 218K all on either 5-20, but mostly on 0-20. No leaks, or oil weeping, or oil consumption at 10K OCIs.
 
Oil pressure gauge is on the list. Already have coolant and oil temp. Would be good to see start up pressure and hot pressure on a 0w16. I'm. Not afraid to run much lower viscosity as the test engine will be pulled eventually anyway. Can't stand the 1.8L power, sounds amazing but it's all bark no bite.
 
I've gone up a grade to 5w30 and down a grade to 5w30 in two vehicles lately and I can't say I gained or lost anything of statistical relevance. I thought my Audi was a little quieter on 0w40 but I also went from flagship euro oil to a dexos blend. My conclusion is that I'll go back to the mfg. spec when I resupply but I won't be afraid to use my clearance oil. My Jeep feels like a dog with 40 grade though so I like your idea of trying it in the particular vehicle, especially if you already plan to move on from that engine.
 
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