Fluids and additives

I am about to change my diff, tranny and tcase fluids and wanted first the proper weight oil and next any additives that may help it. i have used Lucas before and it seems i hear alot about royal purple. anyone have any likes or dislikes of either of those? what is the standard oil weight used as well in the motor? anyone use synthetic on an F head?

Tommy

 

I run Amsoil in all my vehicles including my '56 CJ with the f-head. 75W-90 in my front Dana 25, 75W-140 in the rear although 75W-90 would be fine also (both have Lockrites). I run 75W-90 in both the T-90 and the T-case which has a Saturn overdrive. I run 15W-40 diesel oil in the f-head which only gets driven in the summer. With the higher TBN of the 15W-40 (due to diesel rating) it can tolerate the acids that build up with blowby for a longer period of time than the lower TBN oils. This weight is fine for the winter also as it pours at roughly the same temperature as a petroleum 10W. I have run 5W-30 in the f-head without a problem also. If you run Amsoil do not use any additives. Amsoil gives a warranty against any lubrication related breakdowns and this will void their warranty. The additives are also of a petroleum origin so they actually degrade the Amsoil product. As far as I know the only thing you can accomplish by adding an additive to Amsoil is to thicken it up with a higher viscosity product. This does not necessarily give you better lubrication. It actually is of lesser quality than the Amsoil.

 

I use Castrol or SuperTech 80w-90 in the differential, transmission and transfer case. For engine lubrication I use the least expensive 5-30 A.P.I. certified oil I can find, more times then not its SuperTech made by Quaker State and sold by Wal-Mart for 87 cents a quart.

 

From personal experience, do NOT use synthetic oil. It WILL ruin your engine.

 

Lynn, here is a thread that talks about synthetic, non-synthetic, filter, change intervals and also some of the damage that MAY develop when changing from a non-synthetic to a synthetic in a HIGH mileage engine.

http://www.earlycj5.com/forums/showthread.php?t=9923&highlight=motor+oil

 

Ain't buying that one. Too much info out there too the contrary. I've used for years, no ill affects.

 

Well I'm going to have to say that maybe changing from non-syn to synthetic oil on a high milage engine did me in. The engine ran fine up until the switch to synthetic oil.

 

Sparky, I didn’t read the thread I was just going by recall and thought it was in that thread. It seem someone here had posted about changing from non-synthetic to synthetic on a high miles engine may cause seals to leak, no proof just remember reading that here. As you said the older seals may have needed to be changed anyways.

I do recall reading recommendations of not using synthetic on high mileage engine that had been using non-synthetic right along.

Without doubt synthetic oil is the better of the two so the question is, does the price justify the need? My history of driving habits dictates that I use non-synthetic.

 

I think syn lubercate better but a local speed shop proved that it DID NOT pull heat out of parts like conventional oil did , which cause broke vavle springs in racing motors. No on a daily driver I have mixed feelings about. I use vavloline in my rides 10-30 winter 10-40 summer but thats just me.

 

Ok, I thought it was in there just had it backwards.

Post 28 by 66cj5

however the owners manual and factory manual both say that if you use the syth, you MUST continue to use it, or change ALL the seals in motor.

 

I had no idea how many miles were on my '56 when I bought it 11 yrs ago or so and I immediately switched it to Amsoil. I've used Amsoil in everything since 1992 including my Expedition that had 83,000 miles on it when I bought it. It now has 133,000 miles on it. This dino vs. synthetic oil issue gets beat into the ground all over the internet. I bought a 1991 Cherokee 6cyl with 33,000 miles or so on it years ago. At exactly 50,000 miles I switched to Amsoil after flushing the engine first. I sold it with 153,000 miles on it to a co worker. I used this Jeep to pull my '56 to the trails on a trailer (5,600 lbs) for many years without a problem. My co worker had a dealer mechanic friend look the Jeep over before he bought it and he told him to get a compression check. My co worker knew I only changed the oil 5-6 times in that 103,000 miles with Amsoil. The compression was on the high side of what the Haynes manual said was acceptable. That engine didn't burn any oil in the 10,000-12,000 mile filter change intervals I used. He refused to run Amsoil and a few months after he bought it he complained to me that the rear main was now seeping. I don't know why this happened.
One thing that needs to be considered is that petroleum oils develop much more sludge. Synthetic oils will clean that sludge away over time and contaminate itself with the sludge. Thats why you should flush the engine before switching to synthetic. When the sludge gets washed off the seals it exposes cracks in the seals which allow leakage. This can't be helped. Now if the seals are only hard and not cracked yet the Amsoil will often soften them up and make them pliable again ( I don't know if all synthetics have a seal softener). Dino oils have a seal softener also but because they don't protect from heat as well the seals fail sooner. This is a long post and I don't mean for it to be. If someone wants to PM me I can tell more of my experiences with synthetics. I know my experiences aren't of interest to everyone this thread.

 

I get all my oil from the Kmart refinery!