Amsoil 15W-40 HDD&M -vs- Amsoil 5W-30 HDD

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Pete:

My truck had 37,000 miles on it when I started using synthetic oil. I first used Amsoil 15W-40 for 9000 miles, then with 46,000 miles on the odometer I started to use Amsoil 5W-30. For the 16,000 miles I've been running the 5W-30 a total of 5 qts make-up oil have been added.

 

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FWIW I was at the Oregon State Fair yesterday and spent some time in a Amsoil dealers booth. They were recommending the 5-30 and running about 3 times the DC interval with oil analysis, so about 22. 5k between changes if the analysis supports it. Two guys in the booth at different times also told me to put it in from day one with no break in. They pointed out that many new engines (gassers for sure) come from the factory with it already in the engine. It makes sense to me to break in first, but how are the gassers getting broke in. Is the Cummins really that "not broken in" when new? I am not arguing, I just see a lot of information that conflicts. BTW, I am considering the Amsoil now, where before I was just thinking of going with a good conventional oil at more frequent changes. The beast should be here soon.

Shelby

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Ordered 2001 2500 QC LB 4WD, ETH, DEE, 3. 54 gears, Laramie SLT, Camper Special, Trailer Tow, Travel Convenience Group, Power Driver Seat, Alarm System, Remote Keyless Entry, Fog Lamps, Cab Clearance Lamps, HD Transfer Case, Bright White with a Gray Interior.

E-Brake goes on @ delivery time, Bed comes off and will be replaced by a custom aluminum work body / flat bed. Ordered on 03-28-00. Re-ordered on 08-08-00 (at least I got a VON already the second time)

 

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Shelby - I don’t think you would really hurt anything by using synthetic oil from the start. Both Mobil and Amsoil recommend replacing your stock lube ASAP. Use of synthetic oil from the beginning can extend engine life to some extent, but at the cost of extending break-in time. Engine break-in involves a smoothing out of metal surfaces that takes place via 2 different general mechanisms. Surface irregularities can either be worn off directly or the metal surfaces can "flow" as the result of heating. Synthetic oils generally have higher extreme pressure lubricating properties (ie. the 4-ball wear test results) and they also conduct heat better than conventional oils. So engine parts take longer to reach their optimal design tolerances. This is not much of a problem with gas engines which are manufactured with tolerances closer to specs than long lived diesels.

Many members have reported that fuel mileage for our Cummins improves significantly up to at least 10,000 miles. In my own case, I found that mpg leveled off between 10k and 13k, so I switched to synthetic at that point. In one of my cars that used Mobil 1 since new, the mpg did not level off until 65k. I think that any slight increase in engine life span resulting from using synthetic from the gitgo is outweighed by reduced fuel efficiency while the engine is still fairly new.

A Cummins counter man once told me that synthetic oil prevents proper ring sealing. I really don't understand how that can be the case. Maybe he meant that synthetics delay proper ring sealing.

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1999 Quad cab 2500, SB, SLT, 4X4, 5-speed, 3. 54, tow and camper package, Lance 820 camper, Lance cabover stabilizers, Rancho 9000s, Airlift airbags

 

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Vaughn, the single bypass will provide lubrication to the engine (24v), providing you plumb the return line into the valve cover... albeit, not the ideal place to return the oil.

Some have voiced concern about remote mounting the full flow filter (as is the case with the Amsoil Dual Bypass system); I would like to point out that many different vehicles have their filters remote mounted. A few that come to mind; EVERY S-10 and Sonoma with either of the 4. 3 liter engines (regular or enhanced), most (if not all) heavy construction equipment using the Cummins Diesels, and Diesel powered motorhomes. I know there's more however, these are just some that come to mind.

 

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some of the 5-30/15-40 stuff is also covered HERE

I LIKE the idea of not having the filter mounted to the shakey beast, I think it's less likely to have a failure. Not to mention it's MUCH easier to change.

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tedstruck 2500qc, no leather or abs
bigfoot & other travel pics 1500 bigfoot, no auto waterheater or microwave.
Cool Summit Pass Pics, & Alaska Journal
AMSOIL Battery Mounted Dual Remote

[This message has been edited by ted kidd (edited 09-06-2000). ]