Quote:
Originally Posted by 333pg333
Had a quick read of this article and am impressed at it's thoroughness. However I don't have the time (read mental capacity) to take it all in. Can we cut to the chase and get the recommendations? We use a VR-1 25w/60 for racing Down Under but have left it in the motor for the occasional road use. It does get changed on a regular basis of course.
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Can't speak to the products you may be able to find locally, but for this is my Cliff Notes version of the situtaion with USA products that appear to be acceptable:
Buy and use whatever you want. It used to be true that "oil is oil". But be aware that motor oils have changed and not for the better.
A bit of history:
Prior to the mid 90s most cars on the road had flat tappets to actuate thier valves. It turns out there is a huge amount of pressure on the tappet/cam surface when it is actuated. This effect was discovered in the '50's (I may have the wrong decade but you get the picture) and a minor outfit called SAE noticed that cams were wearing out very quickly.
SAE paid some PhD's to do some research. They published lots of research papers and found out about these high pressures. They also found that a Zinc/Phosphorus additive known as ZDDP would provide protection to these parts at a resaonable cost. Gosh those guys were smart!
The SAE folks spoke with the API folks and asked if they could require ZDDP added to their required oil formulations to increase the service life of these critical components. Much to the pleasure of SAE, API agreed and based on the PhD recommendations, required about 1200 ppm of Zinc (Zn) and Phosphorus (P) added to oil formulations so the oil maker can get his product API certified.
This worked great but then in the 90's car makers went to more expensive Roller tappets which offered the advantage of lower reciprocating losses in the engine (i.e. better gas mileage). The use of roller tappets became standard in cars in the mid-90's.
In the early 2000's, the USEPA (for what ever reason) became concerned that the Zinc and Phosphurus in the oil would partially exit the engine via the tail pipe. This is a big deal since these two elements tend to kill the catalytic converters and, in theory diminish their service life. As a result EPA wanted the reduce the Zinc and Phosphorus in motor oils.
Fortunately (for EPA), car makers had already gone to roller tappets. Again the PhD's went to work. The clever PhD's found that the roller tappets do not exert the high pressures that flat tappets do. They did some more reaserch and found that for car with Roller Tappets, you could safely reduce ZDDP to a much lower level with no adverse impact on cam service life.
This change was codified in the API SM/CJ4 (and newer) oil standards. And while some formulations are permitted to have higher Zn and P, the cost of ZDDP relative to base motor oil is much higher and if the oil maker wants to save some money (i.e. increase profit or lower price) he merely needs to reduce the use of this relatively expensive additive and still claim conformance to API requirements.
Older engines (pre-mid 90's) STILL need high levels (around 1200 ppm plus correct level of detergents) of Zinc (Zn) and Phosphorus (P) to protect cams and other high pressure surfaces.
Use 20W-50 or 15W-40 oil. Brands frequently sugggested here, in no particular order, include:
Brad Penn 20W-50
Valvoline VR-1 20W-50
Kendall GT 20W-50
SWEPCO 15W-40
Royal Purple
Redline
Motorcycle Oils
There are others as well.
This post here may be illuminating as well:
http://forums.pelicanparts.com/5347692-post1347.html