Hi all, I'm new at this board. The data on this whole site really amazed me. You can't find many places to ask such a 'veird' question. It has been discussed at various places that an diesel oils are designed to withstand with higher pressures, higher levels of oxidation, and have better detergency. I have this tiny (2.8lt-173cu.in) old fashioned Canadian V6 GM for all of my driving, no catalytic converter, carburated and has hydraulic valve pushers. Does not use any observable amount of oil (5w 30 -either dino or semisynth). But I never exceeded 5K km.s/3K miles with same oil in the carter. Very nice engine and I want to use it as long as I can. Unfortunately I have to do many miles of stop-go and short trips besides the 70+ mph hiways on a humid coastal area. Anyway, I found a real cheap dino 10w 30 diesel only (API CH-4) marketed as brand Ford (yep, the blue oval...which makes me think it has more than trace amount of moly:)). But no API S_ standardization is stated on the bottle... Somewhere I've heard that the diesel oils are preferrable for classics and old ones which used rarely. I would like to stock some of this oil while it is avaible and cheap. So, do you think can/should I use this oil? Without sacrificing any benefits of a standard SJ dino? Remember no catalitic conv. and HC levels on exhauts are already low (~255 ppm on cold engine before a tune-up due). No residues, engine is clean I guess, after 3K miles oil is still translucent (if not transparent) with some brown tint. In my area 5/30s are pricey because very few cars requires it (you know...supply/demand trivia). Besides 10/30 is almost impossible to find to use in the summer. Last summer it hit ~90+F (40C) several times. I'd appreciate any insights... Hope I didn't bored you with too much detail. In short I just wonder if CH-4 dino could be used on an old fashioned spark ign. engine.