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Oil Analysis - Gas Engines

Discussion in 'Engines' started by W. Arthur, Sep 27, 2011.

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  1. W. Arthur

    W. Arthur New Member

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    Due to flat tappets, as well as maximum bearing-coat protection I use 15W-40 Valvoline Premium Blue HD Diesel Oil and 4 oz of ZDDP (Zinc Dyialkyl Dithio Phosphate) in my good condition 1977 twin 350 cid / 255 hp Mercruiser inboard direct drives. Annual temp range in engine room where boat berths – 55f to 85f. Also, if more than a day has elapsed between run times I bring oil pressure up twice for a count of three via starter alone before allowing engine to fire off and start.

    When I change oil this winter, I plan to send samples of each gas engine in for analysis. Therefore the oil will have the fullest extent of contaminants possible.

    Question: For most accurate reading, is it best to send oil for analysis at end of usage span or in mid span?

    Thnaks, W.
  2. Capt J

    Capt J Senior Member

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    End of the season for best analysis, also take it out of the engine warm after the engines been running 20 minutes. In order to really know what's going on, you should do a sample every oil change. The oil you're using is fine, I have no experience on your additive.
  3. W. Arthur

    W. Arthur New Member

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    Thanks Capt J, for input!

    ZDDP IS SPECIFICALLY FOR LUBRICATING CLASSIC MOTORS WITH FLAT TAPPETS/LIFTERS... it also improves the lubrication film on bearings.

    Most newer engines (around 1989 and beyond) have roller bearing lifters.

    I recomend visiting: ZDDPlus™ - ZDDP for Classic, Muscle Cars & More

    ZDDP will clog/ruin Cat Converters, and therefore can not be used in many newer vehicles.
  4. K1W1

    K1W1 Senior Member

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    Hi,

    Running a Heavy Duty Diesel Engine Oil in a gas engine should deliver an interesting set of results alright.

    I would be interested to know if there are any alkaline corrosion issues from the use of this oil.
  5. W. Arthur

    W. Arthur New Member

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    Me Too!

    HD Diesel oil (even with today’s altering oil compositions) still has high volume of Zinc compared to gen or even high grade automotive oils... which have drastic zinc reduction as compared to pre 1989 oils. Adding 4 oz of ZDDP increases that diesel oil zinc count considerably higher. Detergents in diesel oil are for breakdown and suspension of contaminants, which I’ve observed generally, keeping motor parts free of buildup. I feel diesel oil / ZDDP mixture I use is good in classic motors that have some hours/miles on them and do NOT have exhaust through catalytic converters. Most pre 1989 gas engines tappets/lifters had flat bases; post 89 most went to roller bearing lifter bases. Oil compounds have altered accordingly and now automotive oils simply do not include ample shields/films (i.e. zinc) that address the sheer “rub” that occurs on cam lobes to old-style tappets’ flat bases. Also, I believe my oil mixture would not be conducive to proper lubrication of ANY engine that was too often run at high temps and very high rpm for extended periods. I baby all my classics and do not over work them!

    I use the same lube mixture in: 1967 430cid / 360hp / 10.5 to 1 comp / 118K mile Buick Wildcat engine... 1985 350cid / 325hp / 9.75 to 1 comp / 80K mile 1 Ton 4WD Chev Silverado Truck... 2 – 1987 350cid / 235hp / 330 hr Chris Craft engines... 2 – 1977 350cid / 255hp (one at 200 hr since full rebuild, one at 200 hr since new top end – both had 1000 +/- hrs at rebuilds) Mercruiser engines. No engine uses oil and the oil stays amazingly clean in each between changes.

    I've been using this oil mix in all my classic engines for over 3 years. No prob to date! :D
  6. K1W1

    K1W1 Senior Member

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    Hi,

    Maybe you should re package it and sell it as a specialist snake oil at a largely inflated price to other classic enthusiasts.
  7. W. Arthur

    W. Arthur New Member

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    I'm NOT jumpen inta dat "Snake Pit"! :eek: - LOL Each to their own re lub-combos! ;)