mark4000 Posted April 10, 2016 Share Posted April 10, 2016 Just a quick question, I have a 2010 Subaru forester 2.5 turbo and use Royal purple synthetic oil, which they claim you can go 10-12,000 between oil changes due to how good their oil is. So, was just wondering how long I can push my oil changes due to that claim and due to the cost of Royal purple oil? I'm asking because I heard every 3,750 for a Subaru turbo, which I could see for sure with regular oil. Quote Link to comment Share on other sites More sharing options...
matt167 Posted April 10, 2016 Share Posted April 10, 2016 6k miles TOPS.... Don't fall for the purple dye. it's not magic oil.. 'pushing' an oil change on a turbo is going to end up with a blown up turbo.. Subaru requires/ recomends synthetic for the Turbo models at least back to 2004. 1 Quote Link to comment Share on other sites More sharing options...
mark4000 Posted April 10, 2016 Author Share Posted April 10, 2016 Okay thanks, wanted to be safe on it. Probably gonna go every 5k to be safe. Quote Link to comment Share on other sites More sharing options...
Bushwick Posted April 10, 2016 Share Posted April 10, 2016 Do it every 3k miles with full synthetic like Mobil or Valvoline if you actually care about the engine and want it lasting. Turbos put the oil through hell, as it goes from engine temps to exhaust temps then immediately back into the engine. This will break the oil down quicker over time, causing it to degrade. Having run turbo'd engines myself, even top-shelf synthetics are BLACK around 3k miles, and can be junk before that if you like to get on it a lot. There's going to be a LOT of junk engines in the future from people getting lazy with oil changes and these ridiculously thin weights auto manufacturers have been suggesting. Quote Link to comment Share on other sites More sharing options...
jp98 Posted April 10, 2016 Share Posted April 10, 2016 (edited) Go to Blackstone Labs web site and order their free oil analysis kit and when you do a oil change pull a sample and send it off to them to see what is going on with your oil. They will be able to tell you how many miles that you can run the oil. As a example I run straight dino oil in a Ford 7.3 turbo diesel engine and am running that oil for 5000 miles and they say that I can go to 7000 with no problem. Also on synthetics it isn't the oil that is the problem but the filtering. It isn't uncommon to find those that are running a synthetic to change the filter at 3000 miles and then top it off and get their oil change interval up to 12,000 miles. Edited April 10, 2016 by jp98 Quote Link to comment Share on other sites More sharing options...
keith3267 Posted April 11, 2016 Share Posted April 11, 2016 A guy in Australia got his hands on an old tester used to measure wear resistance on various oil. In his tests, the Royal Purple was one of the best oils for wear protection. Only some very high dollar racing oils beat it, and because of their high viscosity, they aren't suitable for street use, only track use. But wear resistance isn't the only thing thats important. Thermal breakdown is just as important if not more important. As oil breaks down due to heat, it looses its ability to protect against wear. That is why we change it as often as we do. Also at the time, the Royal Purple would not upgrade to SN designation because the SN oils had less ZDDP and Molylith in them and those were the primary anti-wear ingredients. All the SN oils have now found newer anti-wear ingredients and are better and I believe Royal Purple has now upgraded. Anyway, my point is that for a turbo engine, you need an oil with the highest thermal breakdown temperature. If you can find a chart anywhere on the internet, they used to be there but I haven't found any lately and the specs change every few months as oil companies try new (improved?) formulas, I suspect that the European spec oils (BMW, Mercedes, Porsche) 0w30 oils will be the best as they have to be a Group IV oil. Quote Link to comment Share on other sites More sharing options...
mark4000 Posted April 11, 2016 Author Share Posted April 11, 2016 A guy in Australia got his hands on an old tester used to measure wear resistance on various oil. In his tests, the Royal Purple was one of the best oils for wear protection. Only some very high dollar racing oils beat it, and because of their high viscosity, they aren't suitable for street use, only track use. But wear resistance isn't the only thing thats important. Thermal breakdown is just as important if not more important. As oil breaks down due to heat, it looses its ability to protect against wear. That is why we change it as often as we do. Also at the time, the Royal Purple would not upgrade to SN designation because the SN oils had less ZDDP and Molylith in them and those were the primary anti-wear ingredients. All the SN oils have now found newer anti-wear ingredients and are better and I believe Royal Purple has now upgraded. Anyway, my point is that for a turbo engine, you need an oil with the highest thermal breakdown temperature. If you can find a chart anywhere on the internet, they used to be there but I haven't found any lately and the specs change every few months as oil companies try new (improved?) formulas, I suspect that the European spec oils (BMW, Mercedes, Porsche) 0w30 oils will be the best as they have to be a Group IV oil. Got me some Royal purple 5w30 for my oil change the other day ago. It is showing API service SN and says meets Dexos1 specifications. I'm glad I bought the 5w30 weight, since your saying 0w30 is best, but don't know if I can get that off of them other than directly from them, since I have not seen that weight in any store. Quote Link to comment Share on other sites More sharing options...
matt167 Posted April 11, 2016 Share Posted April 11, 2016 RP, Mobil 1 and a couple others are all essentially the same oil. RP is expensive dye. Its been proven in testing and the breakdown sheets Quote Link to comment Share on other sites More sharing options...
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