Detergent oil for old engines (was Re: [AT] It's a Cub! Update

[Mike Sloane]

If you think about the path that engine oil takes inside most engines, I 
wonder if the fears of "loose crud" are overblown. In most engines, oil 
is picked up from a tube that extends into the sump, and there is 
usually a coarse screen at the end of the tube to keep out big pieces. 
The pump is usually a strong gear pump that can push pretty much 
anything soft through it, and from there the oil goes to a disposable 
filter of some kind, usually made from a combination of paper and fine 
screen. The screen stops the larger pieces, and the paper part will 
filter out particles down to stuff in the "micron" range. After the 
filter, the oil goes to the crankshaft, camshaft, and any other places 
the designers thought should be oiled, at anywhere between 10 and 60 
psi. If the filter becomes clogged to the point of not permitting oil to 
flow properly, then there is usually some kind of valve arrangement that 
permits unfiltered oil to bypass the filter and go directly to the 
crankshaft and elsewhere. So I would say that the main danger lies in 
not changing the filter a couple of times after changing over from 
non-detergent to detergent oil.

That is only my guess/opinion, not backed up by one shred of actual 
fact. :-) But I run NAPA 15W40 "Fleet Service" oil in everything from my 
smallest lawn mower to my Farmall 560 diesel and my (IH) 6.9L V8 in my 
F-350 truck - maybe 25 machines, and I have never had an engine failure 
yet in about 35 years.

Mike

Almost-Running Deere wrote:
> Just curious, I've read the same thing.  Since detergent oil was common 
> by the 70s what chance is there that these old engines haven't already 
> seen it?  Given that all four of my tractors seem to have encountered 
> less than good treatment (all early to mid 50s) at some point in their 
> life I wonder if the folks who owned them were all that careful about 
> the oil?
> 
> Does anyone have experience where the crud was actually set loose by 
> detergent oi?
> 
> Not meaning to quibble just my thoughts and I'm curious.
> 
> Dana
> SE PA
> 

-- 
Mike Sloane
Allamuchy NJ
mikesloane at verizon.net
Images: <www.fotki.com/mikesloane>

Heresy is only another word for freedom of thought. -Graham Greene,
novelist and journalist (1904-1991)


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