I just bought a new 03 Mazda B4000 (Ford Ranger). I was very surprised to see a 5w30 label on the oil cap. Every Ford I've looked at had the new 5w20 except for the 4.0l V6 in the Ranger. The 2.3l 4cyl, 3.0l V6 (in the truck and the Escape), 4.6l V8, and 5.4l V8 all require (read REQUIRE) 5w20 yet the 4.0 requires 5w30. What gives? I can't figure this out. Is there some engineering difference in the 4.0? I'm sold on the motorcraft semi-syn 5w20 but can't figure out why the 5w30. Sorry for the rambling I'm just perplexed.

Anyone?

 

it dose not matter that much between 530 an 520 they do the same thing the 520 is more racein

 

Answer is yes, there is some difference in the 4.0 to the others, probably some internal differenct like maybe a gear driven time chain, or gear driven cams or something like that. If you used a 5w20, the viscosity would rapidly shear and cause engine wear.

Now I don't know if this is the reason or not, just a summation that the engines are different.

I would definately stick with what is recommended for that engine.

 

Seek and you shall find.



http://www.babcox.com/editorial/ar/ar40123.htm

Also:
Could be something to do with the aluminum head, and heat. Maybe the 5w20 won't stand up to the Hp/torque, which means heat.

 

The 4.0 SOHC was one of Ford's exception engines to the 5w20 move. Ford's internal engine testing showed that this was one engine that could not move to 5w20 and maintain acceptable wear rates. So they stuck to the 5w30 recommendation on this motor.