Hi Everyone,

I recently purchased a '99 F150 with a 4.6L triton V8. The manual says it should get 5w30 motor oil, and I'm wondering if that is still the best oil for this engine, or if there have been changes in oil since the time the manual was written that would make another oil weight better. I seem to see a lot about guys using 5w20, for instance, and it's made me wonder. I've also seen Rotella 5w40 recommended. Thanks for any info.

Metal Guy

 

Hi Everyone,

I posted this in the year appropriate forum, but I'm not sure if it would be better off posted here, so I'm going to post it here too. I recently purchased a '99 F150 with a 4.6L triton V8. The manual says it should get 5w30 motor oil, and I'm wondering if that is still the best oil for this engine, or if there have been changes in oil since the time the manual was written that would make another oil weight better. I seem to see a lot about guys using 5w20, for instance, and it's made me wonder. I've also seen Rotella 5w40 recommended. Thanks for any info.

 

5w20 is what is recommended now, but 5w30 is fine to use in your truck as that was what was recommended at the time any way. 5w40 is a little on the thick side.

 

FYI, the "W" doesn't stand for weight- it stands for winter grade viscosity

 

Ford has back speced the engine for 5W20, which is now the recommended grade. However, you may still use 5W30 if you want.

 

I'm a frequent reader of BobisTheOilGuy forums and this issue is brought up all the time. It originally spec'd 5W-30 but was back spec'd to 5W-20. There has never been any evidence that one works better than the other in this engine so I feel that you are fine either way. I've been using 5W-30 in the summer and 5W-20 in the winter (Ohio).

The thought process with the 5W-20 is so that upon start up oil gets to the valves/cams quicker.

 

Only one thread per subject is allowed, so I merged the two threads. If you wish to have your thread moved at any time, just send me a PM.

 

With a cold engine, 5W20 doesn't get up to the cams any quicker than 5W30. 5W is 5W.

The "W" ratings are at around 0 F and the other ratings are at 210 F.

 

The word cold is relative. A start on a 75 degree F day is a cold start. Oil spec sheets give viscosity at 40C and 100C. The 40C viscosity is MUCH higher than the 100C viscosity. Now lets compare the 40C viscosity of a 5W-20 to 5W-30.

Valvoline Premium Convential (white bottle)
5W-20 viscosity (40C): 50 cSt
5W-30 viscosity (40C): 63 cSt

Yes they both meet the 5W cold cranking spec, but they WILL be different viscosity at common temperatures. Does it matter? Probably not.

 

Thanks for the information guys. I suspected something like that with back-speccing, but I didn't know for sure. The former owner ran 10w-30. There is a slight clacking sound up high in the valve train when you let off the accelerator; it's not that loud, but I notice it. I was thinking that perhaps changing the type of oil would help it. The manual says if the right weight is not used, the engine can knock.

And sorry Bluejay; my bad. Thanks for the heads up.

Metal Guy

 

Okay - use either 5W20 or 5W30, and do NOT use a Fram oil filter.

You can buy Motorcraft semi-synthetic oil and oil filters at Walmart, it's as good as anything, and they are relatively cheap.

 

Ford says use 5w20 i use 5w20...Just me though and I only use motocraft oil and filters on my new engine as well! Thats what came it it from the start thats what im gonna use from now on too! LOL

 

Motorcraft filters are excellent. They are made by Purolator but are NOT the same as a standard Purolator filter (base end bypass vs dome end bypass).

 

Thanks guys. I appreciate all of the info.

 

Me too. Just got my truck and doing it's first oil change tomorrow....