Does my '85 Brat need higher zinc levels in its oil than is typically found todays oil?

Tough to find. The stores don’t seem to care to carry the Castrol I’d prefer with the zinc. 
 

To answer your question , I’d say no it does not need the zinc but if added that would be helpful. 
 

I’m no expert. But I’ve been running 70s EA71s a long time with the oils I am forced to purchase. 95% of the time it’s the non-zinc oil. And I actually use my 1979 EA71 car often. 

I'm a glutton and will be running a high ZDDP synthetic in my EA82T once it's resealed.  I also bought some ZDDP additive to have on hand for el cheapo generic SAE 30 break-in oils.

Run diesel grade oil, it has the higher ZDDP levels. Example: Shell Rotella.

If it's an '85 and still has it's cat converter, be careful. Too much zinc could ruin the converter over time. That said, in '85, the zinc content of oil had to have been higher than it is now? I'm not an expert in Subaru engines, but I know FLAT TAPPET  (usually v8) engines benefit the most from zinc.

In this case, if you have a flat tappet aftermarket cam, it's worth using it up to a point, especially with high valve spring pressures. I think the number people shoot for anymore is 1300ppm or so for cars with NO converter. The old Dino Havoline 10W40 runs almost 1000, and I wouldn't see that being too low. I ran Castrol for decades in an old Datsun, never added zinc, and never had a problem.

Rotella used to be great, but they changed it over time, and the Zinc is sadly not what it once was.

Valvoline VR1 is an awesome oil for classic cars that you can now buy at Walmart- I THINK it's around 1300 ppm Zinc. However, it states...

"It is not recommended for vehicles with catalytic converters"

https://www.valvolineglobal.com/en/vr1-racing-motor-oil-sae-10w-30/

 

Edited March 13, 20251 yr by subaru1988

Thanks, since my Brat came from California it has 2 cats, I'll stick with the current oil formulations.