as its only in the USA they dont have zinc in the oil, so alll aussie oils have zinc.
Ummm... no. Not even close.
US oils still have ZDDP/ZDTP (zinc/phosphorus compounds) in them, and many "classic" oils are available. API standards are reducing levels (globally for all oil manufacturers who use API ratings) for various reasons and as the general market for oil is new cars its not an issue..
The primary issue with Zinc additives is during break in, not general use. In older engines zinc can help maintain but the lower levels are not huge concern for stock type engines, in higher performance (firmer springs and more valve to cam pressure) lower quality (poorer metals) and poorer fit (lower tolerance cheaper parts) applications it is a issue. A typical combination for wanna-bes who want cheaper horsepower and buy on lowest price.
As for "all Australian oils"... bunk. Penrite Everyday 10W-30 is API SN rated, exactly like many US oils.
Industry Specifications : API SN Resource Conserving ILSAC GF-5
Typical Data
Density at 15oC, kg/L 0.868
Viscosity, Kinematic, cSt at 40oC 72 at 100oC 10.8
Viscosity Index 138
Viscosity, Cold Cranking @ -25 oC 5,810
Zinc, mass % 0.085Pennzoil 10w-30 (picked at random from US brands) has
800-850 ppm of zinc (about 0.080 - 0.085%) Amazingly similar to the Australian oil value when the US has "no " zinc... odd.
Pennzoi Racing Motor Oil SAE 25W-50 (again picked at random) has 1980ppm zinc. Available over the counter in the US. HPR 30 and 40, the "better" Aussie oils, have 1570ppm and 1450ppm.... less zinc.
Similar levels of additives based on ratings and no magical oils here... just as you can buy HPR here there are the same type oils there...
The US has 100x the number of muscle cars than Oz and if you think no one there has the same issue and the market is not selling product$ to fill the need you are mistaken. The misinformation on this issue is legend...