While I agree w/ the no engine flushes, the additive statement is not necessarily true. In general maintenance oil additives aren't needed but if you suspect a sludge problem certain one's can aid in cleanup. Many guys on BITOG have used autorx and MMO w/ great success on sludge prone engines and have gotten results including before and after compression tests and filters full of sludge that prove they can work.

 

another option is to seafoam your truck, it will clear your fuel and oil systems

 

Well seafoam in the oil system is effectively a flush which could break loose large deposits and cause damage.

 

Read up on Auto rx and still not convinced. The amount of people and forums calling it a marketing scam cannot be ignored. Me personaly, I will stick to my opinion that oil additives are a marketing scam. On a tangent I work on piston aircraft engines and I have not found an FAA approved oil additive for an engine! I think that says alot.

 

I understand, a lot of the guys on BITOG used to swear by autorx then all of the sudden they switched to MMO and all started bashing autorx. Mobil 1 high mileage is probably the best suited for the OP's needs as it's formulated for high mileage engines and is also supposed to be very effective at cleaning up sludge.

 

Anytime I've ever bought a used vehicle, one of the first things I've done is a full tune-up and fluid change - everywhere, even if the thing had records showing it was up to date.

That would take care of most mpg robbing culprits. Other places to look is for a dirty throttle body, PCV and EGR valves, if so equipped...

 

I've never used high mileage oils so I don't know. One thing I do know is that make sure they don't contain petroleum distilates. They are used to stop engines leaking and work by swelling the seals! This is only good for short term as in the end petroleum distilates wreck the seals and you end up having to re-seal the whole system. Hammer Z71, you have the best idea!

 

Well there are a lot of kinds of petroleum distillates and they all come from crude oil as it is being refined. High mileage oils like mobil 1 HM use seal conditioners not swellers and detergents to clean the engine and seals and prolong the life of them. The seal sweller problem is something from a long time ago which occurred when synthetics were first introduced to cars and they were still getting the kinks out. I agree that a well maintained vehicle is the best way to get good fuel mileage, add a light right foot and an e-fan and all should be well.

 

I would recommend a good tune up. Change your plugs, oh, and by the way don't bother looking for wires, cap and rotor for your truck, you don't have 'em. Each plug has a coil pack for each plug. I would also say, and most people don't suggest it but it helps. Check your tire pressure. Too low and it'll rob you of mpg really fast. Change the oil also.

 

Just changed my PCV valve, old one was gummed and changed from Sheetz gas to Sunoco. Now lets see if my 8.5 to 9.5 mpg gets any better!!!!