What I have always done for high mileage vehicles making the switch to synthetic. Start off with Castrol High Mileage, it conditions the seals, then switch to a 50-50 blend ...

What I have always done for high mileage vehicles making the switch to synthetic. Start off with Castrol High Mileage, it conditions the seals, then switch to a 50-50 blend for an oil change or two and then go full synthetic.

All in what you wanna do. I changed my oil at 1000 miles with synthetic and I will change it every 3000 eventho my dealer says 5K.

Run strictly Mobil1. Change when the oil life guage is around 10- 15%. I always go to dealer for changes cause I'm still under extended warranty. So far they seem to be pretty comfortable with my routine.
Glen

Check the link: Used Oil Analysis #2
6,700 miles, and Blackstone is telling me I need to run the oil farther. It was an excellent analysis, and shows that the synthetic oil (Amsoil) and this engine are perfectly capable of an extended interval. Next change will probably be closer to 9-10,000 miles.

Lots of opinions here, but the proof is in the analysis.

Great information Eric. Thank you!

MACman4 wrote:I have somewhat of a high milage truck in 125000 don't know the oil history....ive heard if you go to mobil 1 too late it can seep thought some seals any experience or options id like to go with full syn if possible -MAC

I got my truck with about 145000 miles, dint know history of its oil changes either. around 148000 change it to mobil1 5 30, and then around 155000 made another oil change. around 163000 change it again using mobil1 fuel economy 5 30. am up to 174000 and gonna change it again at the end of the month. I never had to add oil between oil cahnges, only right after the firts 100 miles or so. my oil changes intervals are of about 8 months, regardless of milage.

i use mobli 1 full syn and change it at 5k witch is what mobil 1 reccomends any way but at least everyone seams to be around the same mileage

I change mine when the vehicle information message says to change it. Us another leading brand synthetic but after 107,000 no issues.

I switched from castrol high mileage to amsoil full synthetic @238k and no seepage, no leakage, no burning. Ive been 3k miles since my change.