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**71CHEVYSHORTBED402** · 05-24-2017, 12:29 AM

I just started using Mobil 1 5W30 full synthetic on my 71. Technically one oil change. I did the same for my 72, but the engine is a bit tired & burns oil, so the next change is the same only 10w40. Couldn't tell you how zinc starved the original engines are. Mobil 1 is declared "900 Nominal Zinc Level, PPM". I have no idea what that means. I can say I used one bottle of ZDDP, read something I didn't like and changed it the next day. There are lots of opinions.

Here's a great study, if nobody has posted it yet. https://540ratblog.wordpress.com/201...-test-ranking/

05-24-2017, 12:29 AM	#7
71CHEVYSHORTBED402 Senior Member Join Date: Feb 2009 Location: Northern Nevada Posts: 7,386	Re: Engine Oil Ranking I just started using Mobil 1 5W30 full synthetic on my 71. Technically one oil change. I did the same for my 72, but the engine is a bit tired & burns oil, so the next change is the same only 10w40. Couldn't tell you how zinc starved the original engines are. Mobil 1 is declared "900 Nominal Zinc Level, PPM". I have no idea what that means. I can say I used one bottle of ZDDP, read something I didn't like and changed it the next day. There are lots of opinions. Here's a great study, if nobody has posted it yet. https://540ratblog.wordpress.com/201...-test-ranking/ __________________ Tony 71 Custom Deluxe, SWB, 2WD, 402, A/C. I developed an assembly guide (kit) for restoring this truck from the ground up, complete with details including full hardware descriptions. Much of the info. applies to all 67-72 GM. My build thread, with some info. about the assembly kit https://67-72chevytrucks.com/vboard/...d.php?t=730025