Do you use Fuel or Oil additives? Are they worth it?

I had an incident about 15 years ago that proved to me additives can help. Had a 1991 F-150, in-line 6 cylinder, very high mileage motor.Had a real heavy dose of STP in the oil.
Late one night, taking my daughter home. On a back-woods 2 lane road, I was playing with the cruise control.For some reason, the engine revved up to a very high RPM, and my oil pressure went to zero on the gauge, and my warning light came on. I turned crise control off, motor returned to normal, but still no oil pressure. I decided to keep running it, trying to get closer to a safer place to stop.Still no oil pressure, motor started clicking, temperature gauge went up, but I kept driving. Went about 3 or 4 miles, motor started running bad. I shut it off, coasted to a stop. Tried to start engine to see if was locked up,and it started with the oil pressure back to normal. drove it home with no problem.
Next day I took it to a shop, mechanic investigated. He said when cruise control over - revved ( not sure why that happened ), oil pump sucked up a piece of gunk that covered the oil pick-up tube, starving the engine for oil. It ran the 4 or 5 minutes with just the STP keeping the parts lubricated.Then when I shut the engine down, the piece of gunk fell off the pick-up tube inlet, and would then let oil be picked up again.
I drove that pick-up other 75, 000 miles, finally died about 325,000.I credit the STP with saving the motor that night.

 

There was an lubricity additive study done a few years back with results posted. When searching for it, found they did another in Jan 2013. Have NOT read the newer or went back to check the results of the old study so have forgotten much. Just wanted to post the link before rolling out.

http://www.dieselplace.com/forum/76...uids/469425-new-lubricity-additive-study.html

As far as oils, synthetics in the trans/diffs & have NOT found a gain in adding anything to the engine oil resulting in improved oil samples, fuel economy or reducing cost. So just use Mobil Delvac 15W-40.

 

Anti gel if it less than 15 degrees. Thats it. 3.5 million miles on 4 tractors, including 1.5 million on this one, original rears and transmission. Pouring the stuff in is the classic placebo effect. If it makes you feel better, do it.

 

Only time I use additives is when the temps are, or are expected to be in, the single digits or below zero...I like the Power Service product, but will use the Howes if that's the only choice. So, fuel additives have a purpose, to keep the fuel from freezing in the filters in really cold weather...The additive manufacturer would like you to buy their product year round though, so they try to claim it will "increase your mpg"...It will increase your mpg, in winter conditions, but will have almost zero effect in warm weather, so they can claim a fuel mileage increase while only partly shading the truth.

But what about motor oil additives?? I want the best oil money can buy, and I buy that. I buy the best motor oil that I can.

I buy a quality motor oil, and I don't dump crap in with it. The lubricant engineers spent a lot of time formulating the oil, quickest way to mess that up is by listening to some boutique marketeer and buying their "miracle additive" stuff....

http://web.archive.org/web/20100926133335/http://www.bobistheoilguy.com/images/lucas/lucas.htm

Make sure to read all the way through....