This is for my 2005 F250 V10 4x4 now with 26k miles.
Ok guys I have been using Motorcraft 5w20 oil and filter ever since I bought my truck. I have been changing the oil every 3months or every 3k but I never got 3k in 3 months some times I only have 400 miles in 3 months but I would still change it.
Now im using full synthetic and I have only about 350 miles on it and its been 3 months do you think I should change it or wait a little longer?
Thanks ~Gage~

 

I run AMSOIL and change either 25,000 miles or 1 year. I usually only run about 10,000 miles a year so it equals 1 change a year.

 

Definitely wait longer!

How much longer....
Is it sitting a lot, or just really really short drives?

 

There is a school of thought that says the primary factor to consider for when to change oil is how many start ups it experiences.
After that, significant adjustment factors are:
- condition of engine: If a lot of wear (blowby turning oil black quickly), change more often.
- environment. If dusty, change more often.
- frequent short hops. Trips under 10-20 miles are hard on oil as it never gets a chance to fully heat up and burn off water. Change much more often.
- and lastly, mileage.
An engine in good condition, driven on the highway, never on short hops, could easily go 20K miles on a good synthetic oil.

Regardless, your oil should be fine for a minimum of 500 start ups or until it looks really dark or black. Or annually if it sits a lot.

 

In my experience, the biggest enemy of an engine that is used for short/irregular trips of insignificant mileage is condensation. After a while, you will accumulate enough condensation to actually have water in your crankcase! Okay, this is an extreme situation but I have seen this happen to low mileage autos and the first symptom is usually a worn out camshaft. Granted this was on OHV engines but I would imagine that much condensation would not be good for any design. We used to change oil on our exceptionally low mileage vehicles twice a year, regardless of how little mileage. It was often enough eliminate premature mechanical repairs with the low mileage vehicles.

Lou Manglass

 

I would run it for quite a bit longer. I put full synthetic in my V10 back in oct 31st 2008 and still have it in now with around 3200 miles on it. The full synthetic in my 74' F-100 has been in around two years with around 200 miles on the oil/filter and the oil still looks, smells and feels good.

 

I usually take it out on weekends, I mostly use it for trips, 90% of the mile are hwy miles.
Thanks for the info guys.
~Gage~