4x4WSO

Has anyone changed to synthetic on a vehicle with a lot of miles. I just picked up a truck and I want to extend the engine life and maybe improve gas mileage. It's a 1994 5.8L 4x4 with 181k. Runs great but just hoping to keep it that way. Thanks

2002FX4

Do it. I would.

timmy1991

Yep do it. Castrol synthetic gtx high mileage is what i use in my truck and im pushing 300k miles.

hotshott

I would start with a synthetic blend for 5 - 7 thousand miles. Then go full syn. Sythetic oil is thin out of the bottle and you will want to ween it in slowly. If your ride does not like the blend you will know right away. Valvoline also makes that recycled garbage. Stay away from that. It is what is says,,, Used motor oil.

sdmartin65

Hotshott I'd tell you that your a little off with your opinion(and oil knowledge) but that would be taking it easy on you.

4x4WSO

sdmartin65, are you saying go straight to full synthetic is not an issue? I've heard the transition can be rough on an engine.

sdmartin65

I was commenting on hotshott thinking rerefined oil is low quality. Has he never seen what crude oil looks like? As far as synthetic oil switch the truck could be fine or start to leak like a sive. Internals would be fine if maintenance has been decent up to now with no major sludge to break up.

hotshott

sdmartin65, My recent post was based on my experience with Full Synthetic oils. and not my knowledge , or lack thereof where motor oil is concerned. But just for the record, I spent 4 years at ITT Tech. in Houston Texas on a Scholarship from General Motors. When I left college I could rebuild a turbo350/400 3 speed auto trans with a blindfold on. As much as I disliked GM products I took a job with Eaton industries in Pontiac Michigan assembling manual transmissions. At the time, Eaton Industries was owned by GM division of Saginaw Power Transfer. I was hoping to go to work for the Ford Engine assembly. Away from home for over 8 years I decided to apply for a transfer to Eaton Industries Chicago Heights Facility ( The Ford Toploader 4 speed manual was assembled here along with numerous heavy duty truck differentials) and to move back to the area where I was raised. I was transferred to Electro Motive Division of General Motors Corporation. Countryside Illinois. I spent the next 28 years building Diesel Locomotives and I can assure you that I have seen my share of oils/fluids and the like. To this very day I have never owned a General Motors product even with a substantial employee discount. As for never seeing crude oil, You got me there. My dream of working for Ford never materialized. I never collected a dime of pay from FoMoCo.. But I have no regrets for having spent most of my life thus far working for an auto maker, And especially one who's products I never endorsed. I currently turn wrenches part time for a plumbing contractor in new construction. I have been around quite a few blocks in my day so don't worry about taking it easy on me. No offence taken.

Basswacker

I just switched over 120k miles. I added 1/3 can of seafood to old oil drove it about 30miles and switched over to synthetic so far no problem.

I have heard that with high mileage vehicles going to synthetic can wreak it because it loosened all the solid gunk

sdmartin65

Hotshot wasn't trying to a putz, but when I re read might have across like one. Not my intention. Back to the subject, rerefined oil has been used in motor oils pretty exstensively for at least the last 10 years. It can be brought up to the new oil ASE specs which are partial synthetic because of how refined they need to be.

If a person were to use synthetic oil the main benefit would be going to a extended drain interval. I'm sure most owners in this section couldn't bring themselves to go past 5000 miles. Most conventional oils and filters will hold up fine for that period.

I have a customer with an airport shuttle van using synthetic that never changes the oil. He has a dual filter setup and changes them every 10,000 miles. Takes 2 quarts of a 6 quart system to top it off. Three vans one with over 350,000 miles.