New supersport engine and oil

[simonwelton]

Assuming I can get some petrol (ha!!) I intend to fit the engine to my superlight kit this weekend, rather than pour 40 quids worth of Comma Syner G away in 500 miles time, is there a cheaper and better alternative for running in? If a decent oil doesn't wear away too much metal in the first place, surely if I always use a good oil the engine will remain tighter?

Si

[captain chaos]

Engine builders have always told me that a cheap oil is best for the first few hundred miles as it helps the metal surfaces to bed in properly before treating them to some super slippery synthetic stuff.

I am sure others will comment.

[Simos]

Hi Si,

 

you definately should not use a synthetic to run-in, not because it is more expensive but because it will not do what you want it to do.

 

The running in process is one of bedding in, but at a microscopic scale and because of this you want a bog standard mineral oil.

Said oil will protect your engine from what you might call "general wear and tear" at shopping car revs and speeds, but is not SO good that it will prevent the microscopic bedding in.

 

Once you've done your 500 miles drain it out completely (change filter) and fill with synthetic which will then give you the better lubrication to maintain your engine in it's newly run-in state and protect you from the massive pressures generated by blatting revs and speeds.

 

Running in does not wear your engine the way 50,000 miles does and the additional tightness you talk of is not necessarily a good thing. Although machining these days is so much better than 10 or 20 years ago they're only machined to an external standard, what you're doing is microscopically machining the moving surfaces internally relative to each other where they'll be working for the next X years.

 

In my racing days we'd spend 20mins running in on Castrol R before switching to Shell super M during qualifying and the race then we'd rebuild after 1 1/4 hrs, or maybe 2 hrs for a circuit that didn't pull too many revs.

 

What you're also doing is work hardening the bearing surfaces etc which is a process that can't be done outside the car and why you don't thrash it or labour it in the process but build up the power over the 500 miles. Oh and min revs are as important as max revs, above 2k but less than 4 (or whatever your engine builder tells you).

 

Have fun smile.gif Simon.

[Nick]

A guy named Peter Boegli posted this on a newsgroup a while back which may be of interest:

 

I recall having been to the Porsche Test Centre in Weissach some 25 years ago. There I saw them taking performance figures of _every_ new engine for the 911 on a number of test benches. That meant screaming 7000 RpM under full load and for about a minute. Compare that to what many manufacturers (including Porsche) ask you to do during the running-in period! I then asked one of the engineers about the discrepancy in attitude. This was his answer,

which seems to be general enough to be still valid today and for different brands of engines:

 

The main area of concern in a brand new engine is the cylinder walls, i.e. their initial roughness, which reduces the effective area of contact between piston and cylinder. As a consequence the thermal combustion energy (the part which is not transformed into mechanical energy) will not flow through piston --> cylinder wall --> water as efficiently as required. If you keep

the period of high power output short enough, i.e. a minute or so, no harm will be done, because you just accumulate the heat in the piston. It is imperative though to give the engine a longer period of light load and of low speed to cool down again. Because most car manufacturers feel that their customers would not stick to the "one minute max" rule and get carried away

chasing fully run-in Mercedes on the Autobahn they set up the restrictive running-in rules. After all they want to avoid warranty claims.

 

Lubrication is less of a problem, according to this engineer: The cylinder wall roughness is in fact good, because it collects more oil. Pressure lubricated bearings in general have no metal-to-metal contact once the oil reaches them with sufficient pressure. This again requires that the oil has reached operating temperature.

 

So this is what I did running-in a number of Lotus Twin Cam engines, up to now with no apparent defects: Always warm up the engine before going over 3000-4000 Rpm. This takes 5 Miles on a hot summer day to 12 Miles in winter. The water temperature gauge is a bad indicator, as the water heats up more rapidly than the oil. It's an oil thermometer that you need if you want to be sure. During the first 500 Miles use the car lightly, i.e. stay in lowish engine speed ranges for most of the time. A _burst_ of speed will not harm the engine, provided that it is short. During the following 500 Miles gradually extend the "bursts". E.g. accelerating through all gears up to -

well what's the speed limit in GB - seems fair enough to me. Then hold the speed and let the engine dissipate the heat. In general use the gearbox and use the engine, but don't get carried away demanding high stress levels for prolonged periods.

[Roger King]

Si,

 

Our general recommendation is to run in for 500 - 1000 miles on a non-synthetic oil (not a cheap one though). Castrol GTX is good for this. As others have stated, it is all about removing material at a microscopic level. During this period do not drive very gently or very hard and try to vary the engine revs and load levels as much as possible without revving the nuts off it.

 

Once this is done, change to synthetic and have fun.

 

We find that this is the best procedure for most engines.

[Red SLR]

I took my superlight to John Noble for its 500 mile svs (at 810 miles) and they took out the running in oil which was a funny green snot colour.... and replaced it with fully synthetic, when I asked about the running in oil they basically said exactly what everyone else on this thread has said. They told me if I change the oil before the next svs to use either mobil 1 or castrol or similar as the engines need the best quality oil they can get.

 

Simon.

 

 

X777CAT