Hello everyone, I mostly read & learn here (some really great stuff). I race in a flat track series on a modified Honda CRF150F air cooled bike. The rules state the displacement must remain stock, but pretty much everything else is open. I wont get into all my mods here, other than flat track is pretty much wide open so the motor is working hard & I live in the desert southwest. Our ambient temperature range during the summer is 90-102F & 50-75F during the winter months. Currently I run Rotella 15w-40 & change it after every race weekend. My question is on a air cooled motor that only runs at race speeds but has such a short OCI am I ok w/ the 15-40? or should I move up to a 20-50 like M1 especially during the summer mons. Unfortunatley the more I read here the more I questions I have. Ohh & no I have not done an OCI yet, but I will here shortly. Thank you!
Air cooled single RACE engine, Rotella question?
- Thread starter Metric_Twins
- Start date
- Status
I think more useful than a used oil analysis would be if you had an oil temperature gauge installed, or some other way to know oil temp. That's really the only way you'll be able to get a good feel for what weight you need, IMO.
I would have synthetic in there, no question.
I Think a 15w40 is fine...in the "old days" a racing 40w single grade was the typical oil used in motorcycle racing. 40w was still considered a thick oil, even during the summer months here in the South..ahh..the sweet aroma of Castor bean oil.
50w might be used..in a long endurance event..or if there was some signs of wear (usually in the valve train) after a long racing weekend. Most of the time..if you were replacing camshafts or cam followers after a few hundred miles, it was not a 40w vs 50w problem...it was something else.
Multi grade oils were not the racer's choice..I don't think the technology in multi grade oil's were ready for the abuse of competition.
It started changing in the late 70's/80's and I remember being shocked by a very fast Moto Guzzi. The builder used a multi grade oil in competition..the engine was very reliable and produced some very good power.
They claimed the multi grade oil helped the engine generate a little more power reliably..and it needed all the help it could get..being a twin cylinder push rod engine with a drive-shaft.
It worked for them..the oil was Mobil 1. It was not 20w50 as I recall. Early Mobil 1 was something like a 5w40 and very thin to pour.
Today..I don't think Mobil 1 is an answer..it was radical 30 years ago.
You might even try 5w40 Rotella too..compare the stopwatch between the thinner 5w40 and 15w40..and see if your times improve. You might find another horsepower or two with 5w40.
I doubt you will have any reliability problems with either oil
I did not flat track..but I did kick the rear wheel out intentionally road racing.
Good luck!
50w might be used..in a long endurance event..or if there was some signs of wear (usually in the valve train) after a long racing weekend. Most of the time..if you were replacing camshafts or cam followers after a few hundred miles, it was not a 40w vs 50w problem...it was something else.
Multi grade oils were not the racer's choice..I don't think the technology in multi grade oil's were ready for the abuse of competition.
It started changing in the late 70's/80's and I remember being shocked by a very fast Moto Guzzi. The builder used a multi grade oil in competition..the engine was very reliable and produced some very good power.
They claimed the multi grade oil helped the engine generate a little more power reliably..and it needed all the help it could get..being a twin cylinder push rod engine with a drive-shaft.
It worked for them..the oil was Mobil 1. It was not 20w50 as I recall. Early Mobil 1 was something like a 5w40 and very thin to pour.
Today..I don't think Mobil 1 is an answer..it was radical 30 years ago.
You might even try 5w40 Rotella too..compare the stopwatch between the thinner 5w40 and 15w40..and see if your times improve. You might find another horsepower or two with 5w40.
I doubt you will have any reliability problems with either oil
I did not flat track..but I did kick the rear wheel out intentionally road racing.
Good luck!
I've had great results with Mobil 1 5W-40 TDT turbo diesel Truck. It has plenty of ZDDP and is a very robust oil.
However, I don't know how that engine is built. Is it a plain bearing crankshaft or roller? Certainly it's cam and follower design is demanding of quality, high ZDDP oils.
It sounds like your oil choice is good, and plenty robust, especially with the oil change intervals you use. Typically, synthetics perform better in air cooled engines, due to excellent performance at very high temperatures.
It's not unusual for air cooled engines to generate "normal" oil temps of 240 deg F, in normal conditions. That same engine in racing applications may achieve even more temperature. Modifications for more HP will only add to the heat load. This is where a synthetic will out perform a conventional oil. Even a "thin" synthetic, like M1 5W-40. It retains viscosity very well at elevated temperatures.
Just an FYI, ZDDP (zinc-phos) levels of at least 1100-1200 are required for camshaft and follower protection. Here is a list of Mobil 1 oils.
http://www.mobil.com/usa-english/motoroil/files/mobil_1_product_guide.pdf
The M1 10W-40 Motorcycle oil is also a very high quality oil, and exceptionally robust.
However, I don't know how that engine is built. Is it a plain bearing crankshaft or roller? Certainly it's cam and follower design is demanding of quality, high ZDDP oils.
It sounds like your oil choice is good, and plenty robust, especially with the oil change intervals you use. Typically, synthetics perform better in air cooled engines, due to excellent performance at very high temperatures.
It's not unusual for air cooled engines to generate "normal" oil temps of 240 deg F, in normal conditions. That same engine in racing applications may achieve even more temperature. Modifications for more HP will only add to the heat load. This is where a synthetic will out perform a conventional oil. Even a "thin" synthetic, like M1 5W-40. It retains viscosity very well at elevated temperatures.
Just an FYI, ZDDP (zinc-phos) levels of at least 1100-1200 are required for camshaft and follower protection. Here is a list of Mobil 1 oils.
http://www.mobil.com/usa-english/motoroil/files/mobil_1_product_guide.pdf
The M1 10W-40 Motorcycle oil is also a very high quality oil, and exceptionally robust.
Last edited:
MT,
i think your oci is perfect. and i see no reason why you should switch.
just remember, with ever bite of food you eat, you can thank SRT for keeping the tractors, combinds and semi's turbo diesels running!
i think your oci is perfect. and i see no reason why you should switch.
just remember, with ever bite of food you eat, you can thank SRT for keeping the tractors, combinds and semi's turbo diesels running!
- Status
