Various companies make engine oil that are supposed to be good for 15,000 miles or even more.

Amsoil and Mobil make long interval oil.

I've never left motor oil in the engine for much longer than 5000 miles even with synthetic.

 

I wouldn't trust any filter for more than five.

 

It's all about how you drive. If you mostly drive highway miles, you can stretch out the interval quite a bit. I drive 28 miles each way to work, 25 of which is on the interstate at 70mph. I am VERY easy on the oil, and use full synthetic for 7500 miles. If I used the EP Mobil1 or Amsoil I might consider changing at 10K, but still not 15K.

As long as you use a good filter, such as the Motorcraft or Mobil1 filters, there is no reason they can't last at least 7500, and I have the used oil analysis results to prove it. Multiple analysis results, with several different kinds of oils...including Amsoil TSO, supposedly good for 35K miles. I tested it at like 15K I think and it was worn out. My best results have been Pennzoil Platinum 5W30 with Motorcraft filter.

 

I currently run Amsoil 0w30 and find it to be the best oil I've ever used according to Blackstone Labs. Personally, I'll only go 10,000 miles on ANY oil and/or filter even though that's probably nothing for this oil. I also run the Amsoil filter as well.

I agree completely.

 

Judging from the black oil (and its sort of solvent type smell) I catch in my BKU oil separator from blow-by gasses (when the dipstick is perfectly clear), I wouldn't want to run my oil for too extended of a period regardless if its pure synth or not. IMO

 

When I was putting 20-25k miles a year on a single car, I'd go with extended drain intervals on synthetic oil, mostly Mobil 1, but I used Amsoil for a couple of years as well. I'd typically go 10-15k miles between oil changes, and change the filters at the halfway point. There have been plenty of oil analysis results posted from end users that show a good synthetic oil will last past 10k miles.

 

****, your commute is about as long as mine.

 

I wouldn't recomend it if you want to hold onto the car for a long time. I would stick with a max of 5k

 

The synthetic oils won't break down in those intervals , but it does get dirty and with the close tolerances in the VCT on these cars I change it at around 5K for that reason ...

 

ford states 7500 miles between changes I believe and they use part syn oil. A full syn oil can go to 10k easy.
here's a test done years ago. I know not our engines but a test none the less.
http://neptune.spacebears.com/cars/stories/mobil1.html

 

Not to mention most European car manufactures oil change intervals are 10,000 miles with fully synthetic oils. I know the oils that they use aren't as good as Amsoil, Royal Purple, etc etc. In the end it comes down to you doing what makes you happy. This oil topic/debate will never ever die and be 'settled'.

 

Ford states 3k miles for the motorcraft semi synthetic and state 5k with full synthetic, at least last time I checked.

 

No, they state 5,000 for severe service and 7,500 for normal service. Ford says nothing anywhere about using full or semi-syn oil and using different intervals for different oils. The recommended interval is based on the Motorcraft Semi-Syn oil, so any oil that meets or exceeds it in performance will be fine for those intervals at least.

 

Ding! We have a winner! The oil itself is fine, but motor oil carries dirt and other crap like combustion byproducts, which is what discolors it. The oil itself will be fine. But synthetic oils aren't somehow immune to the stuff that gets in it.

I run Redline oil myself, and personally after much experience woudln't touch Mobil 1 with a 20 foot pole. In fact I'd run dino oils first and have plenty of reasons why--most notable horrible hot idle oil pressure with 15/50 M1 that was literally HALF what is was in the same car @ the same oil temp with 10/30 Castrol GTX.

 

This could be interesting. While I have also run Redline oils about 20 years ago( without issue) and have run Mobil 1 in 5 street cars for about 20 years including my present 05 GT( on the street only) I should would like an answer to your whack above Sam. Maybe in competition Mobil 1 is not the best out there but you seem to have started this so I have to ask......What's you issue with Mobil 1?????

 

I wouldn't! Oil is cheap insurance and I change my and the filter every 5000 miles FTW~

 

Unfortunately Mobil 1s quality has decreased over the past few years according to a lot of independent tests. Not saying it's a bad oil.

 

Here is a site to visit where you can find out just about anything you ever wanted to know about oil, filters and additives used in automobile engines, transmissions and rearends.

http://www.bobistheoilguy.com/forums/ubbthreads.php

Happy Reading