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This might be a stupid question, but whats the impact of doing an oil change on a cold engine? Does it just take longer to drain the oil, or will it not drain completely? Ive only ever done oil changes on a warm engine before.

I havent started my NA for 2-3 months now, and need to do an oil change on it this weekend. I just need to work out whether i need to hook up the battery first and either idle it, or go for a trip around the block?

I see no problems at all as the thickness/stickiness between cold and hot oil is not noticeable. Doing it cold avoids the problem of burnt fingers. Just leave the pan under it for a bit longer and let it drip.

From my limited knowledge of oil
Oil does 3 primary tasks: cooling, lubrication and keeps the engine clean.

Warm engine oil picks up sludge and containments from around the engine and transports them to the filter.
Particles that are too small to be filtered out are kept in suspension in the circulating oil.

These same containments drop out of suspension when the oil cools, normally ending up in the sump.
When you drain the cool/cold oil, those containments don't always flow out.

Once the new oil warms up it then picks up those same containments and circulates them through the engine again.

Another property of oil is a corrosion inhibitor (stops rust) for the inside of the engine.
The only way the oil can get to all parts of the engine is when it runs and the oil is splashed around.

Question is, why change the oil if you are not going to start the engine either before or after?

Thanks for the feedback guys.

I ended up doing the oil change on the cold engine, then hooked up the battery and took it for a quick spin around the block. Ideally i would have gone for a warm up trip before starting work on it as well, but i had limited time.

Ive been told by the 'boss' that its probably in my best interests to finish our home renos before i start working on my car, hence why its been sitting in the garage for a couple of months. However, i wanted to give it a quick oil change and get it running as the rego is due for renewal next week.

ps. Pleasantly surprised that it fired up first click and ran smoothly after 2-3 months idle. I really miss my baby