I have an engine that i need rebuilt. I need assembly lube but nowhere close sells it and waiting for it to ship here is not much of an option. Should i use normal 15w-40 engine oil that the engine is rated for on my surfaces or should i use a thin coating of 140 gear oil. The gear oil is thicker but i am concerned it would remain in the engine long term(like it does in diff gears) or clog up the tiny intakes on rod bearings and such.

2 Answers 2


If you plan to rebuild the engine, then run it straight away, I would go with engine oil.

My plan was to always spin the engine on the starter to build oil pressure without the plugs in, then fit and start the engine.

For an engine that will sit before use, I would use a graphite lube that would not disperse and I always found very effective.

  • Even though there is a specialty lube product, I have always used MolySlipG with molybdenum disulfide.
    – John Canon
    Commented Dec 14, 2019 at 19:36

Also you should pull the fuse to disable the fuel injectors as washing your bores and onward, eg cat converter, with gas is not helpful, removes oil, burns in cat etc fuse for the fuel.pump should do the trick.

  • Engine oil with a bit of hi qual moly grease / lube on big n small end sounds good to me.
    – Tilius
    Commented Dec 14, 2019 at 20:51

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