I have a 2003 f250 with a 5.4 with 261,000 miles on it. question i have will it hurt to go to a 30 weight oil? only reason i ask it is starting to use a little oil and its getting valve noise when its hot. thanks in advance

 

Changing the oil weight may help. I would think if burning a significant amount try using a 10w30 instead of the recommended 5w20. At the same time the 5w20 will be thinner and lubricate better when cold.

 

Might try 5w-30 I just don't want to jinks something that has been so dadgum reliable.

 

Mine has about the same amount of miles. Napa had a sale on oil but they only had 3 quarts of 5w-20 and 3 quarts of 5w-30 (same brand/make), so I bought what they had and mixed them, figure it should equal to 5w-25 now. She had a tap but has been quiet since doing that.

 

Have you ruled out exhaust leaks or broken exhaust manifold studs?

 

No issues going to a 5w30, that is what I have been running fo rears and it used to be the spec for the modulars. You will gain nothing running a 10w30 over a 5w30.

 

I have been running 5-30 in both of mine for years with no issues. How much oil is yours burning?

 

It's reasonable to think that, but I've heard the oil stratifies -- separates into layers of 20-weight and 30-weight, like it would in a jar. It doesn't mix uniformly if you combine different weights together.

Now, what the consequence of that is, I'm not sure.

 

I have heard that to but Mobil 1 says it is ok to mix them so I figure they know more than I do.

https://www.mobiloil.com/USA-English...scosities.aspx

 

theres a ford TB or Sb that says you can run 10W40. I'm using 5W40 mobil desel and am very happy with results.

 

Running a CJ4 diesel oil will do damage to your cats. On the bottle it says something along the lines of "not for use in catalyst equipped engines".

I think 40 is too high for the oil passages in the engine. If you live in a warm area it might not hurt anything.