Running/breaking in engine oil

[fetuhoe]

I agree with conditioning a new cam although I think 20 minutes is a long time and the axle stands were a surprise.

It seems that recommended speeds and times are generally on the increase but I would prefer to run an engine at zero load for a minimum amount of time.

I wouldn't add 2 stroke oil to and engine as an aid to break-in.

It clearly won't do much harm as it has been used in Racing Motorcycles for years but I just don't believe it will help, so why bother.

2 strokes are notorious for seizing almost instantaneously and anyone who has ridden a bike with a Villiers Starmaker will know.

Oddly, one of the most common causes of 2 stroke seizure is lack of piston ring lubrication.

Lubrication is at best marginal so why risk all the carbon deposits that can be created.

[smallspeed]

I know its not necessarily relevant to a road car, but the "running in" process on the engines we used to build for BTCC was to get them running, check everything was ok, then thrash the t**s off them for 15-20mins.. then change the oil and filter and run them through a light-medium load cycle for about 24hrs before putting them on the grid. All done on a dyno of course! The old oil went in the workshop heater - environmentally friendly?

The "proper" BMW M-Cars were all treated in a similar way - thrashed on a dyno, but rather than running the 24hr cycle they were loaded with software to reduce the rev limit and throttle opening % so the customer ran them in. They then required an oil and filter change at 500, or 1500 miles (depending on the engine). I believe the latest turbo versions don't require this - they don't need to see a dealer for 15,000 miles after delivery which seems like a VERY long time to me..

As someone else mentioned on page 1, its kind of a trade off between bedding in new cams/trays/lifters correctly and bedding in piston rings, bearings, etc. correctly - given the accuracy of modern machining methods though, in my mind at least there's not a huge requirement to bed in the piston rings (certainly not like there was 30-40yrs ago) and so I tend to err on the side of the cams/valve-train

The main concern for me when rebuilding an engine is cleanliness, hence a good quality filter (or a "scrubbing filter" if available) and some slightly thinner oil is a good way of clearing the engine of any debris from assembly. Its really just rock catching as you always end up with deposits in engine oil from normal running anyway, but its still good practice - regardless of how careful you are there will always be some contamination in there. My guess is the "pint of two stroke oil" was a way of thinning oil down for exactly this purpose, however given 2-stroke and mineral oil are probably immiscible its not a great approach! Better to use a proper running in oil - correct weight, right levels of additives to aid gentle break-in of bearing and journal surfaces, etc. and use a correct assembly lubricant when putting it all together

[gridgway]

I think the suggestion re 2-stroke oil is to put it in the petrol, not mix it in the oil?

[smallspeed]

sorry I misunderstood..

[shoestring7]

I just asked myself the same question as I have (yet) another engine to run in. Based on Russell Lewis' advice I decided to buy a cheap-ish 20w 50 and a quick google revealed this:

http://www.eurocarparts.com/ecp/p/car-p ... &1&cc5_251

As the oil matches the colour of the car(!) it felt bad not to. And their 30% off sale today mean the 10l I needed was £50- delivered.

>C

[MT]

All I'd add is the importance of checking the head barrel nut torques when checking the valve clearances at the 100 mile oil/filter change.
Mick