Running in oils

[crowie]

Does anyone have some definitive data on the type of oil (Mineral or synthetic) should be used for running in an engine.
my understanding is that mineral oil speeds up the bedding in process. Synthetics slow this down which can lead to oil consumption, but have no hard data to support.

regards

 

[evelrod]

That is the 'conventional wisdom'. All the engines I have built over the years, save one, were 'run in' on either bean oil or a parrafin base oil. Usually Castrol "R" in the old days and Castrol 20W-50 most recently. The one exception is my latest 1380cc Austin Cooper which has had Mobil 1, 15W-50 synthetic from the start. After the crash last race, the engine was pulled down and shows absolutely NO wear and has exhibited NO problems in a bit over 8 racing hours! It actually used LESS oil than previous engines. It was an experiment based on what I see with the OEM , particularly Euro OEM, using synthetic from the 'get go'. I am not too old to change and I am very cautious about getting all wrapped up in 'wive's tales' or 'urban legends' but, so far, the 'total synthetic' seems the way to go. One caveat would be the absolute need to do a proper build in the first place. If your building your engine out back under the old shade tree...........!

Rod

 

[crowie]

Thanks for you comments.
The reason I see that Euro OE's are using Synthetics for Factory fill is that they also have very very long service intervals and NO intermediate first servie. BMW first oil change on many models is 20000Km. No mineral product will last as 20000Km can take 2 years.

You seem to be sticking with the better oil companies there but why the Mobil 15w50, why not Castrol Formula R10w60?

 

[evelrod]

Availability and cost. I would probably still be using "R" if it were available. I love the smell.
In reality, Mobil 15W-50 does the job and is available at Wal-Mart for a bit under $4 a qt. My days of being sponsored by Empire are long gone and my contacts with Castrol distributors non existant. I race only vintage and no longer contract for other racers, retired ,you know! The cost of oil is no longer a 'secondary' expense. I did try Syn-Tec for a while but I'm back to Mobil 1. So far, so good.

Rod

 

[ecclestone]

I worked as an lubricants engineer with Castrol for many years,The "help" desk was always fieding questions which got referred regarding oil consumption ,either real or imagined on synthetics for run in.It was apparent though that the "Friction modified " oils of the 70's appeared to cause problems. Research with various engine bulders did uncover some problems with ring compatibility/both metalurgical and design/and the cast iron block material of the time . Most important was bore finish, It was discovered that a diamond grit type hone was being used at at least one OEM plant (Nissan among others) This was leaving microscopic craters which retained the oil allowing the rings to aquaplane over the bore surface allowing blow-by,contamination,viscosity loss and subsequent oil consumption. A change of oil control ring wall tension,and a change of hone material at the OEM plants cured the problem. Since then with all the race engines I have personally been involved with ,Formula Vee,Formula Ford and Small high revving Japanese engines, I became a fan of the Flex Hone to ensure a perfectly smooth bore. You know the one with the balls of carborundum on them. Certainly you need a blade type hone to straighten bores,but a finish with the Flex hone was always a must. I have always used Synthetics for break -in and never had a problem. Leak down has always been checked after dyno time and /or 1st few laps and been fine. Incidently friction modified oils are no longer made, The latest API specs of SJ/SI as with previous standards being able to be passed without them.

 

[crowie]

From what I see, there is whole load of difference when your standard passenger car is FF with synthetic compared to that when a race engine is prepared. Though many race builders I deal with have experienced slow bed in on synthetics. In the family car case, lack of load during early run in stages appears to significantly aggrevate oil consumption.
There is a recent trend to more Kw than is needed by anyone, and more importantly, more than can be legally used. In these cases my opinion is that part throttle conditions appear to be leading to oil consumption.
Any thoughts??
Also the current fuel efficient products (ILSAC GF rated) require some FM to obtain their fuel efficiency above the reference oils.