What Kind of Oil Does a Saturn Sl2 Take
Interesting article on the topic: http://www.boss302.com/oil.htm At this point, the second type of lubrication takes over. The oil pump is forcing the moving oil in between the engine's internal components, creating what is called a 'Hydro-Dynamic Boundary Layer'. That simply means oil is moving around by way of the oil pump. With a single-grade oil, the heat from operation thins the oil that is clinging to the upper parts of the engine quickly, much more quickly than the oil in the pan. This reduces its viscosity, or ability to flow and causes the engine to lose its 'Hydro-Static Boundary Layer' of lubrication. Unfortunately, the relatively thick single-grade 30-weight has not warmed up enough in the pan to be easily pumped up to the upper-engine before the 'Static' layer is depleted. So what you have is an engine that has lost its 'static' lubrication, but is not receiving any adequate 'dynamic' lubrication yet. This creates and abundance of wear and tear. This is why most engines from the 50's and 60's would be all used up at around 50,000-75,000 miles. That, and the high sulfur and phosphorous trace elements in the oil. Multi-viscosity oil nearly perfectly solves this problem. By starting out at a relatively thin weight, such as 5 or 10, the oil will be very easily and quickly pumped up to the critical parts of the engine, creating the 'dynamic' layer of protection long before the 'static' layer of protection is gone. Through the use of man-made additives called 'Viscosity Index Improvers' (long chain coil polymers, which are temperature-reactive), the oil will increase its viscosity as it heats up to its full operating temperature. Operating temperature for motor oil is 150 degrees. This 'overlap' of boundary layers of protection is what has enabled engines to go for 250,000-400,000 miles on a regular basis, along with much better refined oil. Basically, it has taken almost all of the wear and tear out of the warm-up phase of engine operation, which is where 75% of all internal engine wear comes from. All is not perfect, however: The V.I. Improvers are man-made additives and are VERY susceptible to the mechanical and very destructive 'shearing' action of the engine. This 'shearing' action actually tears apart the additive package, including the V.I. Improvers after a certain amount of time. Driving habits, engine type and condition make an enormous difference in how long the additive package will function adequately, but 3 months-3,000 miles is a good rule of thumb for the typical city and highway driven vehicle. All city driving (stop and go, idling, etc...) will shorten the oils life dramatically by as much as 33%. Oil changes every 2,000 miles may not be excessive under those circumstances. On the other hand, mostly highway driving at relatively steady speeds on flat paved and dust-free roads is the best condition for your engine and its oil. This may allow you to increase the drain interval by as much as 50%. The wider the range of viscosities on the oil, the less durable and resistant it is to 'Viscosity Index Breakdown'. For example, 10W-30 oil does not have as much 'V.I. Improver' as 5W-30, so there are fewer additives to be broken down by the shearing of the engine. In fact, 10W-30 is by far the most 'durable' multi-vis oil there is. You should try to stay away from the wider spreads like 15W-50, 20W-50 and especially the 5W-50. Also, thicker is not better, no matter what your mechanic or engineer told you. 20W-50 has 40% more viscosity (resistance to flow) at operating temperature than 10W-30. This means that your engine has to work 40% harder just to move the oil around inside your engine. An engine with thick 'oil' produces significantly less power, uses more fuel, produces more emissions and runs hotter, all contributing to shorter engine life. A thinner oil can more easily and quickly be 'pumped-up' to the critical parts of the engine, takes less energy to move it around, helps the engine to produce more power, less emissions, better economy. And the engine will last longer too! This has been proven numerous times in test after test, by many different and highly respected testing facilities. Unfortunately, the rule that 'you can't teach an old dog new tricks' prevents many 'experts' from accepting the facts. Indeed, when I was a kid, it was Castrol GTX 20W-50 in every car I had! In the years since, I have been working in the automotive lubrication industry, (15 years now) have been on the engineering boards of several major motor oil manufacturers. I feel lucky that I was able to 'see the light'.
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Vehicles:
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'95 Saturn SC1 (single owner)
'99 Mustang GT (sold)
'09 Toyota RAV Sport
'09 BMW 135i
What Kind of Oil Does a Saturn Sl2 Take
Source: http://www.saturnfans.com/forums/showthread.php?t=173918
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