My 94 250 has over 200,000 miles it takes 5w30 oil.but what would be the best type of oil to keep this engine running its best for a long time?thanks

 

250,000 miles. I think your answer is right there in your question! Stay with a quality, brand name 5w30!!!

Dino oils, I'd say use Mobil 5000, TropArtic, or Chevron Supreme (5w30)

Synthetic Oil: Mobil 1, Royal Purple, Red Line. Any of these oils, following a 5,000 mile oil change interval, oil filter changed everytime, any engine will last a very long time.

 

I'd stick with whatever got you there in the first place!

 

I agree with the guys, continue using whatever got it to 200K miles.

I'd also add, if it's leaking/weeping at some seals, maybe consider a "High Mileage" formula, in the brand of oil you've been using, as it's seal softners could maybe help slow any leaking, or maybe even stop a weep.

If it's burning some oil, then look to your brands recipe that offers the best volitility, or lowest evaporation loss, & lowest ash number, as the first two may help cut consumption & the last could help cut combustion chamber deposits, if it's burning some oil.

Just a couple more thoughts for consideration.

 

Id go with a Diesel oil,either 10W30 if where you is a cold area.
Or 15W40 in a warmer place.

My truck seems to really like 15W40 in 120 degree Summers or 60 degree winters.

Im a Diesel mechanic and Im very impressed with how clean Diesel engines stay,even after 10,000 hours of use.

 

One added benefit of diesel rated oil, is it keeps engines clean that experience a lot of idling, plus it holds dirt and soot in suspension very well.

If nothing else, if you use a 10w30 oil, add a quart of diesel rated oil (10w30) as your last quart.

I have no problems with diesel rated oils used in any gasoline engine that does not have a catalytic converter. On a emmsion controlled engine that has a CAT and oxygen sensor, I would limit the diesel rated oil to one quart of total capacity.

 

If it's not burning any oil stick with what you've got. If it does burn oil, try moving up incrementally until the problem is fixed. Start with 10W30, then go 10W40, etc. until it's not buring as much oil.

 

I would think that whatever oil has taken you to 200K is probably the one to stick with.

 

I say if you got to 200k on some kind of 5/30 keep using it.