On the question of to use or not to use a friction modifier. If you have a limited slip differential (LSD) then make sure the oil you use has the friction modifier added. I have seen it both ways, from many different brands. If it does not make sure you add it. As for spark plugs for most of us we are going to tune our trucks once in 100--150 thousand miles why mess with it. Use Motorcraft and be done with it. If they lasted as long as they have whats another $10.00.
here is what Ford sent me, also they said they would see if there is any data to support using Motorcraft Plugs.
The easiest answer is that Motorcraft plugs are made to rigid OE specs. and are designed, engineered and recommended by Ford -- no other spark plug brand (including Autolite) can make that claim. I think we have good brand loyalty because many folks recognize Motorcraft is the plug the "car was born with".
I will ask our Engineers to comment on test data as I do not have any. However, I am very confident in the quality of our products given our Engineers must approve and sign off on every part.
Also, Motorcraft recently launched our new nickel alloy spark plugs that fit some new OE applications -- these plugs are lower priced than Platinum and are not offered by our competitors. Check out part #'s AGSF22N, AGSF24N, AGSF32N, AGSF34N. Good coverage at great prices.....
Last, Motorcraft prices are very competitive vs. all major competitors...
Please let me know if you have any questions......
Ford Customer Service Division
Product Manager - Maintenance Team
autolites are not the same but are considered to be the closest to motorcraft. I will always shoot for motorcraft 1st, autolite 2nd & never consider anything else in a ford. What ever you do, don't fall for those plugs with multiple tips or so called capacitors that store the spark. Why on earth would you multiple tips when the spark only jumps to one tip at a time anyways? They do not arch to all 4 at the same time!!!! They are gimmicks that people fall for!!! It's all marketing and that's it.