Thoughts on running synthetic for longer periods?

All the auto parts stores have synthetic sales every month or so. You usually can get 5qts of mobil 1 & mobil 1 oil filter(or similar filter) for $30.


Advanced has Castrol Edge Synthetic & K&N oil filter $29.99
http://shop.advanceautoparts.com/webapp/wcs/stores/servlet/content_august-2010-oil-specials___

 

I don't worry about the 'dark' oil because that is a sign it's doing it's job of holding contaminants in suspension. If it didn't, they'd be settling on engine components forming varnish and sludge. A diesel's oil can be pitch-black within 300 miles of going in-service.

If you're really interested go check www.bobistheoilguy.com forums. There's one on virgin oil analysis and they have identified several oils now on the market (and sold at WalMart) that are perfectly suitable to extended drain intervals. M1 EP oils are one: these oils have a nice heavy dose of detergent, anti-wear and other additives to go with the fully-synthetic oil blend which stays in grade and is perfectly capable of long service life, as you've found.

Especially important is the TBN a measure of it's ability to handle corrosive by-products. These oils have really big TBN's but what maintains TBN in extended service is adding fresh oil during the interval, whether make-up for oil burned or during filter changes.

But I don't care what the oil, anyone going more than 15K OCI's without running some used oil analysis to see how it holds up is rolling the dice. All the EP oils are great but no matter what the Amsoil guys say it's not the oil: it's the engine, driver and environment that is most unpredictable and dictates how long it lasts. The best ultra-exotic boutique oil with a monster TBN will need changing early if there's an injector running a little rich or a small coolant leak or a pinhole in the air filter.

As for me: I go ~10 K OCI's because it lines up really nice with annual emissions/safety inspections. Around here you won't get out of a shop for less than $200 at emission/safety inspection time, so give 'em something you want done and at least you get a little value for it!

 

Hmm...M1 at my WalMart is $25 for 5qt jug; TG3600 is $7 so that doesn't pass the rational test.

And I'd go 10K with M1, but you're 3K minimum with mineral oil is about right IME, (5K is absolute max).

 

I follow the owners manual.

 

Interesting and a whole other topic.

My thoughts:

I don't think Toyota is so flaky as to try to void warranty on the flimsy excuse of not following manual recommended change interval unless it is genuinely at the root of the cause.

It is just incredibly rare that there are bona-fide oil related failures in engines; it doesn't happen these days. Especially in a low-mileage Toyota motor (under 60K for sure), if someone knows of one let us know.

IMHO, the number one reason Mfr's are slow to extend OCI recommendations in manuals is because people just don't check oil levels anymore!

Once you pass the warranty period then you open the whole other dimension: what about long-term performance? People regularly get 200-300K on engines with 15K OCI's so how can you possibly dismiss the practice?