I have been thinking that as my trucks mileage gets up there (just hit 110K the other day) that maybe going synthetic would be a good idea. I know its been covered before but my main questions are:

A. What are the main benifits to synthetic oil? Is is mostly just the oil change intervals? Or will it help maintain seals and/or clean?

B. If i go synthetic can I go back to regular oil? I have heard yes and no and would just like reasons why or why not?

C. Also is there a recommended oil filter?

I had the fluids done in my diffs, transfer case and tranny at 100K mi (so i would remember when ) but when its time to change those again i might so synthetic also.

 

I changed all my fluids to synthetic in my 99 and it runs soo much better. its well worth the extra cost. I use castrol GTX syntec 10w30with a fram synthetic filter.and mopar atf +4 tranny fluid. and royal purple for the diffs.

 

/\ X2 i changed last fall, runs so much smoother than ever, i flushed the old stuff out pretty well before i filled it with the new.

what i did was drain old oil, pull filter, put a new normal filter on, poured in a couple quarts of the new, ran it for a couple minutes, then changed it like usual, with a synt. filter and a gallon of castrol syntec.

 

My '97 always had synthetic oil (Mobil 1) since new (per previous owner). There were some small oil leaks from the valve cover gaskets and such, and Mobil 1's 10W-30 oil is VERY thin for a 30 weight oil. I changed the oil to Valvoline MaxLife 10W-30 (a thicker 30 weight) and it runs very nice now. Quieter than with the Mobil 1 and the leaks are beginning to slow.

If you have to run synthetic, I'd recommend the Castrol Syntec 0W-30. It's a true Group IV synthetic (unlike their 10W-30 Syntec, which is Group III), and is blended on the thicker side of the 30 weight scale. It'll also start real easy in the cold, with the 0W rating. I use this oil, actually, in my Cadillac's Northstar engine (which calls for 5W-30). If I ran synthetic in the truck, this would be the oil.

Edit: I also like the Castrol Syntec 0W-30 because it's an SL oil vs. SM. Synthetic or not, the way these older engines are designed (with non-roller tips on the rocker arms, distributor drive gears, etc), I wouldn't run an SM oil much beyond 3000 miles, and I'm an extended OCI kind of guy (I do 10k mile OCIs in the Cadillac). The rest of the Castrol Syntec line is plain ol' Group III SM oil. I'm not saying it's bad oil...but I don't think you're getting a lot of value added over a regular "conventional" SM oil, which already has a lot of "synthetic" content in it.

Castrol Syntec 0W-30 (and that weight only) is a true Group IV oil, and all of Mobil 1's oil is Group IV. The rest of the "synthetics" like Castrol Syntec 10W-30 and Pennzoil Platinum, et al, are Group III. I wouldn't pay extra for those, personally.

 

And for the filter,I use the Motorcraft FL-1A. It's the same as the stock filter in terms of thread size and gasket seat dimensions, and is a bit longer for more capacity. It's also an excellent value, performing great and only costing about 4 bucks. I use it in the truck and in our Chrysler van with the 3.8L V-6.

 

before you waste ur money and fill ur head that ur truck is "like new" by changing to a synthetic oil, two questions, where do you live is it20 and below alot? Do you race Ur truck? if not your not really gaining much, you still need to change your oil every 4000-5000 miles, yea the oil itselfwont break down as fast, but it still gets dirty...and dont get any ideas buying that engine cleaner crap to get the sludge out, ya think ya had leakey seals nd sludge, wait till ya bust it loose at one time, ur askin for a engine rebuild doing that!

save the extra 4-5 bucks a quart buy somthing nice

 

Go buy lunch Yea, if it's already leaking the synthetic might seep through, while normal oil won't because it's a bit thicker.

 

ehhh that isnt realy true thats based on if ya get a heavier weight oil...and it doesnt repair seals if conventional leaks so will synthetic, friends that are mechanics tell me that synthetic is for racing or extreme conditions..

 

I know it wont make it "like new" and im not leaking that i know of, i was just wondering if it was worth it. Its just my daily driver right now and i might be towing this summer but not much. I will stick to reg oil for now i was just wondering what everyone thought. And no it doesnt get super cold a lot here.

 

I think to fix the leaking you should put some of that gasket sealing stuff in... Now sure if it's any good in an engine, but it might be...