My truck (77 F100 302) has about 34K original miles. Yeah that is the correct number, it was my grandfather's truck originally. The engine runs fine and there are no problems but I know that there is junk in the engine. How could there not be after 32 years with it closed. Is there a way to run something through the engine to clean out the gunk or am I just asking for trouble. We change the oil by the date not miles because it never gets to 3k in 3 or 4 months. Thought cleaning out the junk might make it happier but I am not sure. Suggest something if you think it is appropriate.

 

Drain the old oil & refil with ATF and let it idle for a few minutes, long enough for it to warm up. Drain the ATF and refill with good engine oil.

 

I would switch oil to something like Rotella T dino oil and let the oil clean up any deposits in the engine.

I've used Rotella T 15-40 for at least 30 yrs in engines as old as 1965. It has always done superb. Engines are very clean and I've not found any visible deposits when doing internal engine work.

 

That engine had 10W-30 specified & if it's oil has always been been changed on time, rather than mileage, with a quality product & a good filter like Motorcraft, it's likely clean inside.

You could look into the oil fill area, or maybe pull a valve cover to have a look-see at the top end, to ease your deposit concerns & get an idea of how things look inside & what kind of deposits may be there & how heavily loaded it may be .

There are a number of oils out there now with detergent/dispersant additive packages that can slooooowly & safely tidy up an engine.

Most gas/diesel rated oils will have an enhanced deterget/dispersant & ZDDP additive package that would work for your low mileage vintage engine.

If it's weeping oil at any of it's seals, maybe consider a "high mileage" recipe formulation that contains "seal conditioners" to slightly soften & swell the seals & maybe be able to slow or stop a leak.

Another possibility if your strongly of a mind to add something to the crankcase lube, may be Auto-Rx. It's an ester based lube with a stout but reported safe (by those that have used it) cleaner upper reputation.

I'd not use a solvent based "engine flush" product as there are many other safer choices out there.

More thoughts for consideration, let us know what you find & do & how it turns out.

 

+1 on that idea.. Ya' never can tell - it might be nice/clean inside there. Those engines are easy to work on, so a couple minutes spent yanking a rocker cover will be worth it. If it's in decent shape, run a good HDEO 10-30, like Rotella, and an FL-1A every 6 months or 1 year, and you'll be good to go.

Had a '72 F100 with a 302 and 3-speed column shift with overdrive way back when. If you wound it out in 1st, you could shift into O.D., then back to regular 2nd, then O.D. 2nd, etc... We had a 6-speed!!! Goofy kids..

 

I took a look in the engine today. It is not new clean but there are some slight deposits. Not really crud like I have seen but some buildup. Probably caused by sometimes too much time between running and the face that my grandfather used the truck like a truck moving dirt and wood etc. I would hate to do something to dislodge something and plug the filter or seize the pump but what about a high detergent oil and maybe 2k oil changes for a few? What high detergent oil would you use? Rotela? or something else. I really don't think I should try ATF - thought it would not be as bad as brake fluid I think.

There is little oil leakage. Some at the top of the oil pan in the front but you really have to look for it so it isn't very bad. The crossmember is a little thick from a failed PS host and a former longtime leak in the transmission cooling line to the radiator.

 

Well what kind of deposits do you see, varnish, gum, baked on carbon, soft sludge????

Good grief DON'T put brake fluid in your engine & Tranny fluid belongs in the tranny, NOT in the crankcase!!!!

 

Well the first reply was to run atf fluid till it got warm and then change the oil. The brake fluid remark was about the LT1 engine guy that was in another post that ran out of oil for a change and used a bottle of brake fluid by mistake.

The deposits are a film of oil with goo in it. Maybe dirt, maybe something else. It isn't burnt oil - I have rebuilt a 289 that required a paint scrapper to clean out the engine before you could do anything else to remove the burned black sluge. I would say that it was just the stuff you get running a engine in a really dirty environment and the dirt gets in the engine and makes areas that are a little discolored and viscous like varnish that is dark but not thick. It looks like it would like to be cleaned, but nothing too bad. Just want to make the best decission. The engine is old but runs very good so I don't want to go the other direction but would like to make it as happy as possible.

The truck has sat alot in the past. My grandfather had it and when he died my father took care of it but only drove it a few times a year. When he died my mother gave it to my son and he just turned 16 in April (he is a very good driver and very responsible so not TOO many worries there) so it is finally driven most days and I want it to last for him.

 

Well I'd maybe consider Auto-Rx, as it'll slowly clean things up. It'll also clean up the ring lands & free up the rings, so it should help compression some.

If you don't want to go that route, Pennzoil & Valvolene both advertise oil that'll clean up an engine. One claims it'll clean out 40% on the first oil change!!!!

A gas/diesel rated oil will have extra detergent/dispersants in it's ad pack & should do a good/slow/safe clean up job & it should have a higher level of ZDDP for your older engine.

 

Well we went to Valvoline Sunday afternoon. We put in the high detergent synthetic blend oil. The truck runs well but we got an added bonus. The guy underneath left the gasket off the plug so Monday after about 150 miles we went in and the guy drained the oil and put a new gasket on - all that new oil and any trash it picked up went away. On Wednesday it was still leaking and we went back in. He put the wrong size gasket on it so out cane the oil with about another 150 miles on it and in went a new plug with the right gasket and 5 new qts. In 4 days the engine has been flushed 2 times and that can't hurt the grime inside. And we got it all for free after the first change. I hope we chose the right oil and the engine should be much cleaner now.

 

Good grief, that engine must be dizzy by now, from all of the short run synthetic flushes it's had, but I'll bet she feels all fresh & clean inside!!!! lol

Not many folks can afford to flush an engine twice in 300 miles with synthetic, but at your 3 for 1 cost, not many of us could come close to that deal either.

Well on second thought maybe we might, if we could buy that wrong sized oil pan plug gasket from you!!!! lol

Did you opt for the Valvolene high mileage synthetic recipe????

 

Yes, I got the high mileage. There is some weep around some gaskets on the oil pan, timing chain cover etc and I hope that will swell those back up and stop that. Not that you can see it right now with all the oil that blew over the truck on the trips to the oil store. I do feel better about the internal oil surfaces now.

 

The high mileage recipe would seem to be a good choice.

Will be interesting to hear how the oil weeps respond & how the internal clean up that you can see, goes.