I have been doing a lot of work on my 96, 4.9L. I to the point its just about ready to get a oil change and she is ready to go. I have used i the past Valvoline 10-30 conventional oils and a F1A filter. Recently I read an article on line, from Ford saying my engine should be using 5w-20. Yet, my owners manual defines 10w30. So which is it. Anyone use the 5w-20? I have not had any known problems with the 10w30, but Im not sure why this article would suggest the 5W-20. Yet another article states that Castrol in the preferred brand for engines using conventional oils. I have used Valvoline. IF you have any thoughts or experiences with any of the above, I would love to hear them....

 

Owner's manual is correct.

Read here, post 11:

https://www.ford-trucks.com/forums/1...-question.html

 

Ford issued a TSB (02-1-9) where they recommended switching to 5W-20 for most early 90s and newer vehicles

 

My '85 did not complain about 20w-40. (Or was it 20w-50....?)

A '96 with how many miles on it? It'll probably be happy with anything clean.

 

Mine has 138k. I’m thinking I will go with 5w30, we get dome single digits in Ohio, it might help.

 

That'll work. No single digits here, although some have said something about my IQ and single digits. I don't understand that comment.

 

I understand. My IQ has often been questioned since I have old ford trucks! Envy.....is a terrible thing.,at least that what I tell them.

 

This topic has certainly been discussed a lot this and other sites. The general consensus is use a 10w30 conventional. 5w20 is pretty thin and unless you built it with tight tolerances avoid it. 15w40 is fine unless you are in northern winters.

The main concern discussed is the flat tappet cam. Modern gasoline oils have had the necessary additives severely reduced for emissions purposes. This may not be a huge concern though as modern oils are much more advanced and should be fine for stock cams and spring pressures, just change them liberally. Another popular option is shell rotella t4 conventional 10w30 or 15w40. Its a diesel oil that still has the old school additives for flat tappets. If your engine burns oil and has a cat you may want to avoid it though.

Using a synthetic oil is playing with fire. Lifters need a small amount of friction to cause them to spin, synthetics may make this difficult. Some credible sources I've read say no major oil manufacturers will recommend synthetic or done any real long term testing on flat tappets except for ams oil's zrod oil and royal purple hps oil (which are specifically for flat tappet cams).

Oil is very very complex and I'm not an engineer, this is what I've gathered from many hours researching it though. My recommendations are:

Stock 300 beater: name brand conventional
Mild built 300 or concerns about flat tappet cams: shell rotella t4 conventional.
Wanna spend the big bucks: ams oil zrod synthetic

 

Thanks SO much for your response. It is very enlighting. My 4.9 has 138K on the clock and still has the Cat. I had looked at the Shell T4, but since it is identified as for a Diesel Engine, I did not investigate further. I'm assuming the reason not to use the t4 If the vehicle still has the cat, which it does, is because there may be a potential to clog the cat. Is that true?

I want to stay away fro the synthetics. So Im back to the conventional motor oil, 10w-30. What do you think about the 5W-30? I'm in Ohio, so we get a bit chilly during the winter. I'm sure you can relate. I have no history with the 5w-30, but if you look at the responses one person does.

Additionally, I don't consider it a beater, I try to take care of it. But I know the lack of Zinc could be an issue. At least everything I read, says it is. What's your thoughts on the Oil additives? I know many consider it to be snake oil and it may well be, I don't know. I have been reading about some engine oil additives such as Lucas LUC10063, Rev-X ZDDP and ZDDPPlus. (Plenty of Info about them on Amazon) ALL contain Zinc and are at least marketed for engines with Flat tappet cams. IS it a good idea to use, are they good products, not sure, but I would love to hear your thoughts on it.

Thanks again for writing