OIL

What the original oil recommended for a 1979, L48 engine.  I have been using a 30W.  

On my '81 I've used Mobil 1 15-50 for years for the heavy ZDDP (helps cams & lifters) that is in reduced levels in oils used in current cars.

|UPDATED|2/2/2015 5:35:16 PM (AZT)|/UPDATED|

No one should be using straight 30W.  Where did you learn that?

I use the Mobil 1 15W-50 also.  And I still have a bottle of ZDDPlus if I want to go to a 10W-30.

Manual has a range based on outside temps.  So I see why some are using the 15W-50.  30W is on the range also as an option.  20W-50 has the largest span on the range.  20W-40 or 50.  15W is not on the scale.

Here's the content listing for Mobil One.    The fourth column in give the Zinc levels.

 

To me, racing oil is not designed for passenger car use.  Race cars get their oil changed often, our Corvettes don't.  Also, I don't think the racing oils have the detergent levels that passenger car oil does.

Mobil 1 15W-50 fits the bill for me.  I guess you could also use some of the other ones that have 1100 ppm of zinc.  And the Turbo diesel oil has lots of zinc and it is an SN rated oil.

   I have ofton thought of using the diesel oil. What is the viscosity of it, and what is the cost comparitive?  THANKS.

Beats me, but you can get 5 quart jugs of Mobil 1 at Walmart cheap.  Nothing wrong with the 20W-50.  I don't think a manual written in the mid 70's for that era oil is valid anymore with today's oil.

Someone school me on the zinc levels?  What is this about?