Start off going 7500 miles. Get a used oil analysis done a Blackstone Labs. They will give you a breakdown of what is going on with your oil for that mile interval. After that, they may recommend going further on the oil between changes.
Go to www.bobistheoilguy.com for all your oil information needs. The forums there have every piece of info you can imagine.
Just to get this out of the way, if you are concerned about maintaining your warranty you need to stick to Mazda's recommended oil change intervals. If warranty is not a concern then you could probably stretch it to 7,000-8,000 miles but I would recommend switching to 5W30 if you want to go that far. I just don't know if I'd be completely confident in 5W20 over that kind of distance, even synthetic stuff. If you want to stretch it further you could use one of the 5W40, 0W30 or 0W40 synthetics formulated for diesel trucks. These oils have higher detergent concentrations and higher total base numbers to keep the engine clean and fight acid build-up over longer intervals.
actually if you read the websites http://www.royalpurple.com/rp-faqs-wu.html they won't ever give you an: "you're completely fine if you do this" type of number. What I mean is, most don't want to say you're ok to go to a certain mile beyond what the manufacturer recommends whether it's synthetic or not. However, if you look at your owners manual you'll find that the factory recommends you go 5K between oil changes on regular. There are definitely some cars that can safely go beyond the 3K regularly on regular oil.
After doing this research for myself before making the synthetic switch, I decided to play it safe and go 6K miles between oil changes. Obviously if you continue to read Royal Purple's website, it's mostly dependent on your driving style/conditions. The best advice is to go up to 5K miles after your first Synthetic oil change, and just check it every time you fill it up at the pump to see how clean/dirty it looks. If you know what dirty oil looks like, you'll know when to change it :wink:
[quote author=S1lverstreek link=topic=135723.msg2925724#msg2925724 date=1234240645]
...just check it every time you fill it up at the pump to see how clean/dirty it looks. If you know what dirty oil looks like, you'll know when to change it :wink:
Just an FYI. The color of an oil means nothing. Some add packs in oils darken quickly, some don't. For example, Mobil1 gets dark very quickly but it can handle long intervals.
The best way to verify the life of the oil is to have it analyzed, as bustednutz indicated above.
By the way, based on UOA's, RP isn't that great of an oil in our engines. If you're going to go synthetic, Pennzoil Platinum has shown and proven to be a fantastic synthetic oil, especially for long OCI's.
royal purple full synthetic....best shit on earth. free's up more available horsepower...on horsepower tv they dyno'd an LS1 camaro and saw a 9hp increase. i love it. i use royal purple in my motor oil and my transmission gear oil..the difference is very noticable. greater and smoother pick up instantly after the oil change..and also to mention shiffting is like cutting a knife into warm butter
Anything but RP. In our 3, I use Pennzoil Platinum which has shown to be a fantastic oil based on an analysis that I received from a third party source after I sent them a sample of my used oil. There are tons of UOA's out there for other vehicles that show the same thing for Platinum. Even if I wasn't using Platinum, I wouldn't waste my money on something as expensive as RP, especially considering our engines are VERY easy on oil. Plus there was a member on this board a while back that sent his used oil sample of RP into the same lab that most of us send to, and RP didn't fair good at all in the analysis. IMO, RP is a lot of marketing and hype (ex: purple colored-oil). I realize that Horsepower TV did their own "testing", but I hardly put any stock into a TV show that is sponsored by the product they are "testing".
im very pleased with RP. The engine runs a lot smoother and i can feel the less "friction". Specially in the transmission. Even if it is 8 dollars a quart, ive used RP in all my other cars and love it..so i stick with it. Penzzoil platinum is a very good motor oil. I think its great. Id recommend Pennzoil platinum to anybody. Im just a fan of RP. Ive always used it, always loved it. to make things simple so you can understand my perspective, i can see and feel much improvement, and i like it. so thats why i use it.
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