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API SJ - suitable oil?


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Sound fine  - looked at my Haynes and Gregory manuals, recommends  SF (1980s - now obselete)  grade  20W/40 - 20W50

SJ  grade (pre 2001 vehicles) sounds fine

SJ  more recent oil and probably additives of a higher standard  than the original SF Grade originally recommended now obselete.

 

http://www.pqiamerica.com/apiserviceclass.htm

Edited by subnz
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10w30 in a 30+ year old EA81 is probably ok if you drive very conservatively, have under 150k miles, and the outside temps are under 90. Go over any one of those 3, in my opinion, you need heavier oil. 

 

Let me point out some basics before I go further. The first number in any XwXX multigrade is the actual viscosity of the oil before additives. 10w30 is a 10 weight oil with viscosity additives that should make it perform like a 30 weight oil when it reaches operating temperature. 20w50 is a 20 weight oil that should perform like 50 weight at temperature. That first, or base number is the only one you can really depend on, and that won't shear, or break down like additives will. That is, if the additives were good in the first place. The quality and amount of the additive (was it mixed in on a Monday after a holiday weekend?) is a complete given that we trust simply because the numbers on the bottle say so, because that's what it should be if everything was done right. That's why serious racers use straight weight oil, completely dependent on what clearances they are running and HP per CC. Multi-weight oil was developed because nobody wants to wait for their oil to warm up, which takes longer than the coolant to warm up. And everyone expects to start their car on sub-zero days, slam it in gear and go immediately. It really has little to do with the outside temperature once the oil is warmed up, but the biggest risk of running too heavy of an oil is just for cold startups. Otherwise, we would all be running a straight-weight dependent on our engines clearances. Thin oil is for satisfactory lubrication on cold startups, that's it... 

 

    But wait! there is a huge second factor involved in this whole equation. Carmakers have to sell cars, that is pretty much their number one objective. And when some schmoe is trying to decide between a Honda and a Subaru (because both cars he saw were a color he liked), if their is one mpg difference between them, guess which one he wants? The entire movement towards thinner oils is all because of gas mileage, and the subsequent pressures from the EPA. It really has NOTHING to do with newer, tighter, more efficient engines. That's all blah, blah, blah.

 

I have run Castrol conventional 20w50 in hot weather my entire adult lifetime. I have never "blown" an engine, in broad terms. To be specific, I've never had any bearing failures. Any time I had an engine overheat, it was fine after correcting the problem. Every engine I've ever owned was passed-on in running condition (exception of a few that rusted up). My daily EJ22, which has over 500k miles, is driven extra hard and has never been down past the valve covers. 

 

So give your old motor some nice thick oil! Just don't be in a hurry to blast off for work if it drops below 50...

Edited by Subaru Scott
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Thanks guys, it was reassuring to read those replies!

 

I hear you Subaru Scott, I never flog a cold motor, when I head off to work my Brumby never get much past 2,300 - 2,500rpm for the first five - ten minutes

And I always take it extra easy if it's been a frosty morning.

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