Oil change interval and type is very vehicle dependent.
On my Passat never go past 5000 miles with synthetic unless you want a new motor. All oils show viscosity breakdown even after the first 1000 miles itt a matter of how tolerant your motor is to thinner oil and how much it thins.
Unless its my Passat then its thicker because the oil tends to sludge up. <img src="/forums/images/graemlins/zombie.gif" alt="" /> There are a number of other modern vehicles that have sludging problems from manufactures trying to push oil change intervals too far.
I change my Passats synthetic oil every 4000 miles... The cost of the oil is a bargain compared to fixing the motor.
Synthetics have a more consistent mix of molecules. Since they donÆt have short ones that cause a low flash point the amount that boils off during running is lower and the flash point is higher.
Those same short molecules tend to swell seals so they work better. Early synthetics did not swell seals so the motors tended to develop leaks. Newer synthetics have additives to prevent this problem.
Many newer oils have less high-pressure additives to reduce contamination of the catalytic converter. Amsoil took the opposite track and added a huge amount of high-pressure additive to their oils. ThatÆs why they do so well on the four ball wear test but also why many of their oils are not API certified.
Is more better? Depends.... Too much leaves deposits on your pistons and kills your converter. I'm not comfortable with the new oils that have almost ep additives in my old 2.6 engine. So far its been ok...
Zinc is contained as part of the standard additive package in virtually every major brand of engine oil sold today, varying from a low volume of 0.10 per cent in brands such as Valvoline All Climate and Chevron l5W-50, to a high volume of 0.20 percent in brands such as Valvoline Race and Pennzoil GT Performance.
Organic zinc compounds are used as extreme pressure, anti-wear additives, and are therefore found in larger amounts in oils specifically blended for high-revving, turbocharged or racing applications. The zinc in your oil comes into play only when there is actual metal-to-metal
con tact within your engine, which should never occur under normal operating conditions. However, if you race your bike, or occasionally play
tag with the redline on the tach, the zinc is your last line of defense. Under extreme conditions, the zinc compounds react with the metal to
prevent scuffing, particularly between cylinder bores and piston rings.
However - and this is the important part to remember - available research shows that more zinc does not give you more protection, it merely prolongs the protection if the rate of metal-to-metal contact is abnormally high or extended. So unless you plan on spending a couple of hours dragging your knee at Laguna Seca, adding extra zinc compounds to your oil is usually a waste. Also, keep in mind that high zinc content can lead to deposit formation on your valves, and spark plug fouling.
I have found that bikes need EP additives esp if the gear box uses motor oil to lubricate it. Motul worked very well in my Kawaski... Regular synthetic Mobil 1 did not.
However Mobil 1 works great in my Raider and Passat.
Kevin
