Mobile 1 switch........how long till next change now ?

JKD,
Where do you have it tested? Often thought of doing this but never have.
I have always thought that the creators of the Jiffy Lube franchize pulled off the advertizing scam of the century when they managed to brainwash the entire nation by recommending changes at 3k when at the time car and oil manufacturers were recommending 5k and most (Toyota included) still do recommend 5 or even more!

I use synthetic in all my vehicles and change the filter also at 6K. On the bike I change @ 3k but that's because it's an air cooled large diplacement and I like to work on it but should check them all the next time around to see if I could go more.

 

This is the right answer IMO. I have done an oil analysis thru Blackstone Labs on 3 different vehicles. My conclusion is that many people change oil way too often; too many are still using 1970 guidelines in 2010- which Auto Zone loves. Today cars run cleaner with EFI; oil is better; automotive gas no longer contains lead.

With conventional oil my 2008 Tacoma had a TBN of 3.0 at 5000 miles on the oil. 3.0 is still very good, the oil has 1000 miles of life remaining, maybe more.

With Mobil 1 my Evo had a TBN of 4.7 at at 4500 miles. This is a turbocharged car and runs a high oil temperature. It has a "real" oil cooler and under hard use the oil temp will still go to 230F (measured at the drain plug in the pan). 6000 miles would be no problem in an Evo driven "normally" (anything but true road racing) so a Tacoma would probably be ok with at least 10k on M1

Wife's 2007 Civic, 5750 miles on conventional oil, TBN=3.9; again, plenty of life left. The oil % life remaining meter in the dash said 30% life remaining which would mean ~7500 miles so Honda's engineers have an accurate algorithm for computing remaining oil life as it agrees with the chemical analysis of the oil.

 

TBN being the measure of the additive package's ability to handle additional acids and prevent corrosion is the effective limiter of a synthetic oil's service life. But adding make-up (due to oil burning, or ideally periodic filter changes) oil boosts the TBN. I've read of some people getting 25k miles on a change. That's when you really need to take oil samples to measure things like suspended contaminants and oil viscosity which is the indicator of how much the oil is shearing down in service and are the ultimate limiter of service life.

Every engine is different. And not just by design, but in service.

Also: people should never think a motor oil that is nice and 'clean' looking is a good thing! The oil's job, in addition to lubrication, is to hold microscopic contaminants in suspension: a clean oil draining out the hole means they are staying behind! That's the stuff that makes sludge and varnish.

I love to see nasty black oil on my dipstick: it means the oil's doing it's job!

 

Thanks for the in depth education guys, great thread!

I'm going to look up Blackstone Labs. I'm due for an oil change in the Taco next month, but first I think I'll send a sample of this batch and see what comes back.

Any thoughts on what extending oil changes might do to a warranty? If an owner was armed with this kind of test info and documentation, I wonder if an auto maker could still dispute a warranty claim? Any lawyers out there in TacomaWorld...

 

I also change oil and filter every 5K You should never have a problem

 

Never!

 

lol, good luck with that.

 

The manufacture has to prove what you did/didn't do lead to the problem to deny the warranty. So if they believe the lack of oil changes caused the problem, They have to prove it with their own analysis. This is hard to prove unless there are signs of neglect on the vehicle (like sludge). If the oil is within specifications when you take it in for service, they cannot say we will not fix it since we do believe you have not changed your oil in 2 years. Your first response should be I do change it regularly, what proof do you have otherwise.

To add context to this. Toyota was refusing to replace blown engines in in 2002 because they said owners neglected to change their oil. When pushed on the issue Toyota said as long as owners could show they changed the oil once a year, they would cover the repair. They did not say every 5000 miles, but once a year.

Toyota says it will cover the cost of repairs if owners can show they made at least one oil change per year. The company, however, is refusing to back down from its contention that negligent owners are the cause of the problem, not a design defect or quality problem. Toyota and Lexus owners manuals specify that the oil should be changed every 7,500 miles or every six months, whichever comes first. Under severe driving conditions, oil should be changed every 5,000 miles or four month

 

I just changed over to synthetic also. Just in case it removes any sludge that might have been deposited while running dino I'm doing the first couple changes early...after that it's 5,000 or 6 months (which ever come first)