SCORGE

As long as the Lucas gear oil meets factory recommended specs, you should be fine. As far as the crankcase additives...no. Just use your recommended weight/viscosity of dino bones/synthetic dino bones lol. I'll just have to priority overnight Eagle a cup of coffee

Martian

If you're asking about just the gear oil itself, yes, go for it. I'm using it in my diffs. It's Lucas's additives that have no place in my garage.

covertness

I've added a quart of this to my oil at every oil change since I bought my F-150 in Dec 2004. I've never had any problems with the engine save breaking the #4 spark plug when I changed them at 90K miles. Currently at 150K miles.

Not saying it's good or bad, just saying what I've done.

Martian

This is exactly the caveat needed. Thank you for including it. Folks need to understand that just because they've done it for years doesn't necessarily mean it's the cause of all their luck.

650NutKase

Make that 2 cups please lol Thanks for the input

650NutKase

Thanks guys. Good info! I'll use the syn gear lube in the rear come change time.

nrivera04

I only use it cause it makes my 7th quart so I don't have to buy a second case of oil haha! Done this for 7 years on my 4.6 and 3 on my 5.4. Like above, I'm not saying one way or the other, it's just what I do.

650NutKase

I went with Valvoline full syn 75w140 only bc they didn't have 3qts of Lucas in stock. It has the Ford spec right on the bottles so I'm content

mikewaco

I just bought a used 2002 F150 4.2L V6, 175k miles. When I was inspecting it for sale I noticed a fairly noisy vibration while stopped in Drive. After crawling under it, I became convinced that it was a catalytic converter. So I went ahead and bought the vehicle, and shortly thereafter took it to a muffler shop, changed the cat, and all quiet except...
With the cat noise gone a new sound became apparent under the same driving condition, stopped in Drive... a dang rod-knock. Naturally my heart sank as I listened to this heartbreaking noise. It was absent at startup, but as the temp gage neared it's normal stopping point, the knock came to life. It would go away if I switched into neutral, but as soon as I put it in Drive or Reverse, and mildly touched the accelerator, the sound of a single cylinder deep knock began its loathsome song.
So I began with an oil change to standard oil, 5w20. It got louder.
After some online reading I changed it to Delo 400 15w40. It got louder still - so loud, I was afraid to drive it. (but still only in Drive).
Then I did the unthinkable (before reading this thread)... I bought some Lucas Oil Stabilizer and maxed out the dosage. By 'maxed-out' I refer to the directions which states that "for badly worn engines use up to 60% of system capacity." Thus I drained the 15w40, and added 3.5 quarts of Lucas, then topped off with the same 15w40. Being in the heart of Texas, it's hot 9-10 months of the year so I thought I'd try this. So what happened?... so far this has given the quietest result, I'm hearing no deep knocks or clicky lifters - until it gets fully hot (after about 15 minutes of driving with the A/C on). A slightly noticeable knock is discernible while stopped in Drive. So I got to thinking, what if I downgraded the thermostat to a 180F temp? Might that keep it out of the knock temp? What other damage might this give rise to? I know these things violate lubrication religion but I'm looking for replies of those who've used the product, and have been down this road (engine rescue) - not the name-callers (snake oil). I'd rather not spend an arm & leg on this engine. I've never done rod or main bearing replacement with the engine in the vehicle. I don't have a hoist and my skills are intermediate at best. I'm also 50+ years old, not as young as I used to be. I feel like I'm close to an acceptable solution, but I think it still needs some tweaking.

Reyn

I havent used it in my Ford but i have a 99 Z71 5.3 that my father in law gave me 6 years ago. He used Lucas oil treatment in it so i just continued to use it on oil changes. It has 312k miles on it now and the engine has never been opened. I just substitute 1 qt of it.