I am going to try and change my bad coupler this weekend. I wanted to know is Mobil 1 5w-30 syn oil ok for this? Thanks guy'* for all of your help.

Good question. One of our members found out that there is a TSB about it. And the TSB says you can.

https://www.gmforum.com/t279121/

Thanks again to TLSheff

There are some write ups in tech info about doing that and they reference being able to use Mobil1

Should I try it? Or should I get the GM */C Oil? Thanks guy'*

Per the tech bulletin it'* okay. The Mobile 1 is cheaper than a bottle of SC oil.

I plan to use it in every SC I rebuild. The last one I did a rebuild on I used the GM snout oil only because I had a bottle.

If I remember right, isn't there phosphoric acid in the OEM oil? I remember it smelling like yuke. There had to be a reason they'd use a corrosive like that. I'm all for the Mobil 1, but that seems like quite a difference to me.

Most likely there is a specific reason or was a reason for it. There is also afterthought which led to GM sending out the pictured TSB in that thread.

The TSB says it is an option. When I order parts etc from vendors, I will probably always buy the SC oil, out of preference. Between the normal cost and shipping it can be a reasonable difference that some might have trouble justifying knowing that GM issued this TSB. My local dealer gives me a great price on it....other folks end up paying close to $30 for two bottles at the dealer.

My thought is that there were very few choices for synthetic oil at that time. Now there are many choices.

Here'* a thought. Doing a oil change with filter is 4.5 quarts. The jugs are 5 quarts. You do a oil change and have half a quart left over. While the car is up and the pan is draining you can remove the SC plug, suck out the oil, then add 8 oz and put the plug back. About 5 mins. Now your oil has finished draining from the oil pan and you can finish the oil change. Changing your snout oil with each oil change is totally easy.

I have just replaced the oil in mine due to not kowing the history of the car, the oil was 5$ cad a bottle at the dealer down the street from me. I thought that was a lot of $$ but guess not