to my knowledge, Using Oil vs an accelerant (ex Carb cleaner/brake cleaner) basically does two different things. Oil is used to plug the vac leak temporarily to see if engine changes, the accelerant will be sucked in and burnt, at the same time will plug the leak a little, not as much as oil.

Oil is very very messy. Unless you plan on degreasing the engine or power washing it after, I wouldn't use it. It will take a long time for it to burn off.

Thats my thought. I prefer brake/parts/carb cleaner/start fluid vs oil.

 

Hey sorry I misread your post. I thought you mentions 10w-40 lol. not WD 40. Sorry.

I would stick with the brake and carb cleaners, after all though. you can try WD 40, It will linger for a while longer and might produce the affect your looking for vs the cleaners / starting fluid. If I was desperate I would use it

 

I recently fixed this problem on my truck. I changed the crank sensor and fuel regulator on the spider injection system. Your 02 sensors will throw po170 and po160 I believe but chances are your cats need to be changed too.