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Re: My rant about oil Posted by sam96CS [Email]  (#852) [Profile/Gallery]
(more from sam96CS) on Thu, 27 Nov 2008 19:43:24
In Reply to: Re: My rant about oil, Abusot, Thu, 27 Nov 2008 16:47:01 Members do not see ads below this line. - Help Keep This Site Online - Signup |
Those are impressive UOA numbers. At 6 months and almost 3000 miles Rotella T synthethic has a stronger additive package than virgin Mobil 1 0w40, based on your sample. With calcium at 2787 the TBN is still high enough to keep the oil from turning acidic. You can probably safely go to a 5000 mile interval with very little engine wear.
For those who don't know, the additive package is the key difference between motor oils rated for gasoline engines and oils rated for diesel engines. Oil changes are usually necessary not because the oil has gone terribly bad but because the additive package has been used up.
Saab 9000s were built between '86 and '98. In '96 the owner's manual specifies the API service classification SH oil, and SH quality oils contain high levels of phosphorus and zinc to serve as a final defense against metal-to-metal contact (think high pressure areas like cam lobes and crankshaft bearings). Oil companies in recent years have been substituting molybdenum disulfide, which is good for catalytic converters and oxygen sensors and also improves gas mileage - at the possible expense of engine life. That may sound acceptable in the abstract, but we talking about the lives of OUR engines.
Newer API service grades have come along. But the API does not specify how well motor oil must perform under the sustained high temperatures that are typical of B2x4 engines. Nor does API specify how long an oil should resist the breakdown (shearing) of the oil's viscosity. Consequently there is uncertainty and heated debates about how frequently motor oil should be changed and which oil is the best for a given application. You have to pay an independent lab to learn what has actually happened to your oil and engine internals since the last oil change.
In addition to satisfying the highest API diesel oil standard (CI-4plus), Rotella T 5w40 synthetic also meets API gasoline engine standards SH, SJ, SL and SM. API SH is the last classification that specifies high levels of zinc and phosphorus. Read some motor oil package labels, and you'll see how hard it is to find an oil that unambiguously provides high enough levels of the zinc and phosphorus additives that Saab's engineers required when our engines were built.
Abusot, I agree with your concusion. Next oil change I'm going with Rotella synthetic.
posted by 71.75.23...
, Sun, 30 Nov 2008 08:15:44, Thu, 27 Nov 2008 13:58:15, Thu, 27 Nov 2008 19:43:24 <-- Viewing This Message, Fri, 28 Nov 2008 07:21:57
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