| 455 Maintenance Specs [message #96559] |
Fri, 20 August 2010 16:24  |
Benny Hill
Messages: 18
Registered: August 2010
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Junior Member |
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Greetings fellow GMCer's,
I am brand new to owning a GMC, the finest motorhome ever made in my opinion. I have a few questions to ask regarding my 455 engine.
Was it originally designed to run on leaded fuel back in 1976 and if so should I be adding lead additive when I fuel up?
What fuel grade is recommended driving here in the Florida heat?
Should I be installing the original spec AC spark plugs or is there a better AC plug number to be using with the new fuels?
I read that some of you are running Mobil-1 15w-50. That is a heavier weight than recommended in the Owner's Manual. Any concerns of it being too heavy on cold engine start up?
Can anyone recommend a good over the counter ZDDP additive to use with non-synthetic grade oil if I choose to go that route?
Can I use a 180 Degree Thermostat or will this cause the engine to run too cold or make the stock clutch fan cycle other than normal? I have no overheating problems that I know of, but am concerned about the engine running on the hot side here in Florida with a 195 thermostat.
Thanks for any guidance you can provide. I am excited about owning my GMC and can’t wait to get going on tuning it up. I thought I should ask the experts first before making any novice mistakes.
Benny Hill
Shopping for a GMC
Florida
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