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Home » Public Forums » GMCnet » 455 Expected Engine Life (Assuming proper care, how many miles?)
Re: [GMCnet] 455 Expected Engine Life [message #360418 is a reply to message #360417] Mon, 30 November 2020 18:10 Go to previous messageGo to previous message
James Hupy is currently offline  James Hupy   United States
Messages: 6806
Registered: May 2010
Karma:
Senior Member
If you are religious about your oil changes and the rest of your
preventative maintenance, keep checking your compression regularly and if
everything measures within 10/15% of each other, my advice would be to keep
doing what you have been doing. New engines can and do blow up fairly
regularly. A well broken in engine with high mileage is a proven product.
If the oil consumption starts to go up, mileage drops, or idle gets rough,
stay on top of it. Those are warning signs.
Jim Hupy
Salem, Oregon

On Mon, Nov 30, 2020 at 4:00 PM Douglas Smith via Gmclist <
gmclist@list.gmcnet.org> wrote:

> "You guys that live in flat country have not a clue to the GMC's
> requirements for climbing grades. You can cover 6 states in a day and not
> break a sweat.
> Try running the Tehachapi grade out of either California or
> Arizona/Nevada, or the Grapevine coming North out of Los Angeles on
> Interstate 5, or the Siskiyou summit a bit farther North. You will run out
> of gears pretty darn quickly. I have a heavy 78 Royale with a 403 and 3:70
> final drive, and it works really well. And I run it at 70 mph + most of the
> time. 3400 rpm and that 403 is a happy camper. Over 130,000 miles on an
> unmolested engine. Works for me.
> Jim Hupy"
>
>
> A question for you Mr. Hupy, et.al.
> I bought my '73 in 1995 with 140K indicated miles. The PO had oversize
> tires on it so I think that's probably an underestimate. The engine, to my
> knowledge, has never been opened up. I have given it regular oil changes
> with Mobile 1, new water pump and timing chain, Thorley headers, new
> quadrajet from Paterson, new Pertronix, fuel and vacuum hoses, and a 4.70
> final. I tend to drive her easy, cruising at 65 mostly, up to 80 only when I
> have to. Oil pressure settles a bit with warmup but the stock sender/guage
> are still quite lively, even at hot idle. I have not done a compression
> test. I'm guessing I've put around 2K miles annually on it since '95 which
> puts its current mileage around 200K. That's a guess for a lot of reasons,
> but probably about right.
> I have not done a search to find out if this topic has been answered, but
> I think engine longevity may be somewhat a moving target with old
> hardware/modern fluids and newer opinions valuable. Is "drive it till it
> dies" a good idea? I was incredibly fortunate to be close to Larry Weidner
> for a transmission failure, I can't expect such luck going forward. Any
> wisdom?
> Doug Smith
>
> --
> Douglas & Virginia Smith
> dsmithy18 at gmail
> Lincoln Nebraska
> ’73 “Canyonlands” since ‘95: "Wanabizo";
> Quadrabag/6 wheel disks/3:70 final/Paterson QuadraJet/Thorley’s/Alloy
> wheels(finally!)/Sundry other
>
>
> _______________________________________________
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