does a 1981 300 I6 take? I dont have the original manual and my service manuals dont go back far enuf - all I can glean is that they insist on SE oil bwahahahahahha

 

Through the years they keep upgrading the oil. I remember SG, SH,..... I have forgotten what the latest letter is now, but it will be in all the stores.

The weight of oil depends a little bit on were you live. The factory always specifies a lightweight oil like 5w-30, because of fuel mileage, and it also works good in very cold weather. I usually use 10w-40 and if I have a engine that is really worn out I will try 20w-50.

 

Here's a link to a chart for the viscosities.

http://www.autozone.com/images/cds/g...3d800ce531.gif

 

I run 10-40 year round in my 82 300 6 & it seems to work well.

 

As Per Original Specifications For All 1981 Ford Engines. Highest recommended comes first...

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Motorcraft Super Premium: 10W-40
Part Number: XO-10W40-QSP

Motorcraft Premium: 10W-30
Part Number: XO-10W30-QP

Motorcraft Premium: 20W-40
Part Number: XO-20W40-QP

Motorcraft Single Weight: SAE 30
Part Number: XO-30-Q


Specifications: ESE-M2C153-B (API SF) or: ESE-M2C153-A (API SE)

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You can't get SE or SF oils anymore though, the current specification is SM.