Way too much info for me. I'm 71 and been a car guy since I was 16. Driven a lot of hard miles and abused a lot of engines. Never had an engine failure that I could directly blame on oil failure. Always went on the theory that regular oil and filter changes were much more important on the specific oil you used. Been using Wal-Mart generic conventional oil of the weight recommended by the manufacturer in my daily drivers for 30+ years with no problems. Will be using Valvoline Racing oil in my T-Bird when I break it in and thereafter.  Used Wal-Mart generic 30W in my small engines for the same period. Recently switched to their 10W30 full synthetic for small engines. I'm not saying this guy doesn't know what he's doing but most of the oils he tested I've never heard of and are not available in my world.

When looking at oil technical data the VISCOSITY INDEX tells you how stable the weight is. The higher the VI number the less it will change in weight from cold starting to  when the engine is at its maximum temperature. A 0w40 will have similar weight to a 15w40 at 100 degrees Celsius but will be thinner at lower temps. The 0w40 will also not thin out as much at temperatures greater than 100C/212F because it will have a greater VI than the 15w40. The further those numbers are apart the more stable the viscosity.  

Order it online.  Amazon usually have great prices.  Jegs and Summit are also good sources and sometimes have it priced better than local stores.  They all offer free shipping for a certain dollar amount.  And I'm sure it can be found other places.
Sometimes you can by it by the quart for less than a case.  Order 6 individual quarts and they'll send a case and it will cost less than a case.  Watch out for that and you can save a couple bucks more.


Lawrenceville, GA

I was planning to go back to Valvoline VR1. I have a limited choice in my part of town. The local parts stores only carry the popular conventional oils for the most part.

Durham Missouri

The Mobil 1 tech for what it's worth still recommended 15W50 for flat tappets with 1300 ppm zinc. It seems to me we have several options to choose from and I can't say if 0W40 is safe or not, I've never used it and from what I can find out it's relatively new even thou the article gave it the highest marks of all the oils tested.
     For now I'm using Amsoil Z- Rod 10W-30 high zinc formula with 1400 ppm zinc with no issues. Applications API, SL, SJ and earlier.


-Gary Burnette-

No idea but most major brands have a 10w40 or 15w40 oil.  Use that and take out the guess work.



Lawrenceville, GA

I was doing some more research on this and run across a post where someone recommend mixing 10w30 with 20w50 to achieve a 15w40 oil weight. Is this a viable option? The post was about the same brand oil just different weights.

Durham Missouri

20w50 should be fine for a Y block.  It should not be needed for a fresh rebuild, though.

0w40 could be too thin.

Here is a website that allows you to compare the viscocity of an oil at given operating temperature.  There can be quite a difference between similar grades.  One brand of 15w40, for instance, could be thicker at a given operating temperature than another brand of 15w40 at that same temperature.  You need the technical data sheet, which you can get from the oil manufacturer.

http://www.jiskoot.com/services/calculations/viscosity-temp/



Lawrenceville, GA

So the 20w50 racing oils are out for y block use? I was thinking about using the Valoline VR1 oil for my next oil change in that weight. I'm using Bradd Penn 20w50 right now but at $50 a oil change its a little pricey. I may try the 0w40 Mobile that Speedpro56 mentioned.

Durham Missouri

This is all real interesting but the real question is how many of us has had an engine failure related to the oil they use? I've been a member here for some time and I can't recall anyone posting "don't use brand X oil because my engine just failed because of it".

Durham Missouri