Is there anything different formula-wise between the old All Climate oil and the new Premium Conventional? Reason I ask,the O`Reilly near me has an old case of All Climate 20W50 and I was thinking of trying to make them an offer on it.
I suspect there were some improvements when it went over to Premium Conventional, if nothing else, maybe it coincided with the transition from SL to SM.
If you can use 20w50 and the price is right, go for it. If it's SL it should have more zddp.
I always get confused about the amounts of ZDDP in 10W-40/20W-50 motor oils when we're talking about the difference between SL and SM. Is there always less ZDDP in these 2 viscosities in the SM version? I was thinking that the levels of ZDDP in these 2 viscosities are not regulated like the starburst oils are. Can someone 'splain the deal on this issue to me? I been wanting to ask this for a while but never got around to it.
I do think that there are enough other improvements to the base oils and additive packages of some of these more viscous SM oils to prefer them overall to the previous SL versions of these convetional oils. Anyone "in the know" on this subject?