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-----Original Message-----
From: Eric Kozowski <eric@svjava.com>
To: Military Vehicles List <mil-veh@uller.skylee.com>
Date: 05 January 2000 05:56
Subject: Re: [MV] First Oil change...
>> As a note of interest Detroit Diesel specifies Mobil Delavon 15-40
>> motor oil only if I remember correctly. If you use it exclusively they give
>> a much better warranty to wit it is REQUIRED for the warranty to stay in
>> effect.
>
>actually, for the 2 cycle engines, detroit specifically recommends
>against using multi-vis oils. for normal temperatures, they recommend
>40wt. around here, guardol 40 (unocal) is what most folks use in
>their two cycle detroits.
>
The DDA manual here takes 5 pages to cover lube specs and requirements, it says
specifically multigrades must never be used in series 149 engines, straight
detergent SAE 30 or 40 being their preference. Series 92, 71 and 53 engines
have 15W/40 as a third choice for operation below 0ºC/32ºF ONLY. The four-cycle
8.2L is qualified for multigrades.
Note, most of the 50's - 60's UK MVs use engine oil (SAE 30 detergent, MIL 2104)
in the gearboxes too. Speaking to the labs of the multi-nationals it is
apparent that multigrade oils are a chemical tweak to extend the operational
temp range but are mechanically weaker than a straight type being rapidly
destroyed in a gearbox. In high consumption engines, typical of the Mil and RR
B Range specifically, multigrades produce a very aggressive ash causing
accelerated wear which is also the DDA two cycle scenario.
Straight SAE 30 is not exactly the old-fashioned glug you might think and media
hyped magic multigrades for the huge domestic market aren't all they seem
either.
Richard
(Southampton UK)
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