4106 oil

[desi arnaz]

I was looking in the owners Manuel ov my 4106. And it tells me to use straight 30weight
Which is not what you guys tell me....my parts guy says to use 15/40 which is ten bucks a gallon... Who is right?   Most people tell me to use  straight 40 weir.  Low ash of course

[RJ]

Thomas -

Detroit changed the recommendation from straight 30wt to straight 40wt sometime in the late '70s > early '80s, and has not changed that requirement since then for the two-stroke 8V71 in your 4106.  (And yes, the Owner's Manual for the 4106 does say to use straight 30wt - so does my copy.)

Your parts guy is correct - for the four-stroke Series 50 or Series 60 Detroits.

Sounds to me like your parts guy is using selective hearing when you're asking for oil. . .

FWIW & HTH. . .

[desi arnaz]

He has a special on the 15 40 $10 a gallon.  Would it cause damage?  Where can I get a good deal on straight 40?                  Thanks!!

[Oonrahnjay]

He has a special on the 15 40 $10 a gallon.  Would it cause damage?  Where can I get a good deal on straight 40?                  Thanks!!

     Yes, 15W-40 will cause damage in a Detroit Diesel 2-stroke.  Due to the fact that you have the cylinder cutouts in your engine, the load on the piston rings is different from the rings on a 4-stroke motor; 15W-40 oil will not protect the rings and cylinders.  You want ONLY straight 40-weight.

[TomC]

15W-40 is actually a 15 weight oil with polymers (think chemical ball bearings) to make the engine think that the oil is a 40 weight.  In a 4 stroke engine, the polymers get squished down during compression and power stroke, but recover during exhaust and intake stroke.  On a 2 stroke engine, the pistons and bearings never relax (during powering)-hence the polymers get squished down-never to recover and you end up with the engine running on a 15 weight oil.  Piston skirt and rings are the main wearing, with bearings not liking the 15W-40 either.  If you use 15W-40 in a 2 stroke, you'll have significant wear by 100,000mi, with maybe a 200,000mi overhaul.  Straight 40 weight can give you a 500,000mi engine.  Good Luck, TomC

[luvrbus]

The spec on DD oils starting changing in the late 60's with the introduction of the 149 series engine that is where all the low ash crap started from by 1974 with the introduction the 92 series it was pretty much std up till then 30w.

I am not even going to touch the 15/40 debate lol

[thomasinnv]

Oreily's auto has delo 100 40wt for 12.99 a gallon. I can always get it next day. The part number is 100-40-1. Some guys say you can run delo 400, that it is less than 1% ash now, but it is also $5 more per gallon. I just stick with the delo 100. YMMV and JMW.