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Old 02-06-2006, 09:20 AM   #44
Bill Hamilton
Mustang owner since 1970
 
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Join Date: Aug 2003
Location: Charleston,SC
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Re: Important Information About Mobile 1 Synthetic Motor Oil For Mach 1's

Quote:
Originally Posted by E-MACH
I wonder about this one. What's the problem with using 5w30? At cold start-up they are both 5w spec for fast lubing, so what's the difference? I know the book calls for 5w20, but since the mod motors run so flippin hot, having 30w protection once it's hot seems to make a lot of sense to me. Motorcraft makes their specified semi synthetic in both multi-weights. Any input would be appreciated. Motor oil is still a dark science with so many authorities claiming cosmic wisdom.
Today's motors like the DOHC 4.6 are built to much closer tolerances than engines in the past and 30W oil is too thick in many cases. When you get a couple hundred thousand miles on it and continue to use it as a daily driver and aren't concerned with performance as well as the engine has worn and loosened up consistently, then by all means use the heavier oil.
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My 1970 Mach


2003 Ford Mustang Mach I---Black w/5-speed --- gone but not forgotten
2011 Shelby GT-500 --- Ingot Silver Metallic and 6-speed (Sold and Now Terrorizing the residents of New Zealand)

1970 Ford Mustang Mach 1---White w/351C-4v Shaker Hood scoop and T-5 tranny
2014 Shelby GT-500 --- White/red stripes and 6-speed
2019 Mustang Convertible Premium Package w/automatic

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