im using sr-1 5w20 on my car now, the engine was rebuilt not long ago.
just realized using a really thin oil can be a good substitution for engine leak test haha :D coz found out got leak after 800km which was not detectable when i was using synthetic 5w30 for 7k then sent back for overhaul warranty. been running for almost 2k ever since with no oil loss
plan to send for uoa after 7k to see if it does harm to my car. if wear is normal, might as well use thin oil.
i would suggest people to use the new amsoil 0w30 signature series AZO, the latest formula has Moly-Phos-Zinc like torco MPZ for anti-wear, calcium, boron and magnesium as detergent. Amsoil is sold at a cheaper price than most high end oil. the TBN number is so far the highest among all oils that i have viewed so good for long interval drain.
a virgin amsoil azo uoa
note the MPZ & BMC compound. TBN of 12.5
im going for amsoil azo on next change coz its cheaper than my current torco
just did checking on torco 5w20 virgin oil analysis, apparently it has way more anti-wear additive than amsoil for people doubting on torco since its not certified, although amsoil has more detergent / cleaning agent compound. number in bracket is amsoil number
Moly 1372 (130)
Boron 1 (232)
Magnesium 20 (12)
Calcium 1712 (3251)
Barium 4 (0)
Phos 970 an SL oil (652)
Zinc 1057 an SL oil (763)
Silicone 7 (5)
VI 100c 7.46 (10.47)
to conclude, if u looking for long drain interval / maintainability get amsoil, but if u like to high rev the engine most of the time torco is the way to go but change the oil every often