Synthetic Oils for Shovelhead Motor
 

Hello I am new to this forum

I am Experienced MC Rider/Wrench owning 1997 Ultraclassic with 1340 EVO Motor. I am exclusively using MOBIL-1 20-50W MC Blend on the EVO motor. I have an External Oil Cooler which promotes good oil pressure the bike loves this product. Simply put no problems loss of oil pressure in traffic or waiting for lights to change to green

My New addition is a 1979 Shovel Head strong runner with only 19,000 miles on it. the Previous Owner uses Straight 60W motor Oil. He claims this is the right stuff for the Motor. I have put an Oil Pressure Gauge on the motor to monitor the oil pressure and performance. When I start the motor the pressure is 50lbs very good and no problems while at speed. I notice when the motor is warm and Idling at 1,000 RPM the Oil Pressure is dropping to 5-10 lbs. I am told this is normal for this type of motor

My concern is whether or not I can begin using Synthetic Motor Oil in the Vintage Motor. I realize there are pro's and cons just looking to get some feedback from the more experienced riders or builders out there. I am concerned about the upcoming winter riding season.

Thank you everyone

Synthetic won't hurt but might be spending more than necessary. I bet the shovel will be ridden less with more frequent stops, not used for touring. You will probably change it with less miles. I would just stick with regular oil and run the proper weight for ambient temperature. If you do decide to run synthetic stick with the straight weights, thats what the older bikes like. The low pressure is normal for all V-twin, my wrench made a comment once, Haley's use volume no so much pressure. So 5-10 psi is normal.

You will get increased wear with a single weight oil as it can't flow properly till the engine warms up. Multi grade oils solve this problem. The only advantage to synthetic is longer life in a bike like a harley with a separate transmission. You can also get away with using an automotive oil in your Harley for this reason. Motorcycle oils, those with a JASO MA rating, have no anti friction additives unlike automotive oils as these cause the wet clutch in a common sump motorcycle to slip. Since a Harley's transmission and clutch have their own separate oil supply and don't share it with the engine this is a moot point for Harley owners. The anti friction additives in automotive oils are actually a benefit in a Harley.

That said, a motorcycle specific synthetic works better in a bike with a common sump that lubricates both the transmission and engine due to the differing lubrication needs of the transmission.

Having owned a new shovel, way back, the only oils recommended were single grades! Your bike will be fine with a decent V-twin multi-grade IMHO.

As for using synthetics in an old engine that seems an unnecessary expense. If you were running a new S&S shovel, that would probably recommend synthetics (my S&S Evo does), but I would advise against using them in your bike.

Very good chance that using synthetic in the ol' gal will cause her to spring a passel of leaks. Two reasons - one is that certain older seals are not always compatible with synthetics, two is that there can be some build-up on the inside of seals in that old a bike and the synthetic will remove it - then the leaks will appear. Just use a good standard 20w-50, or maybe a 25w-60, and have fun.

I owned the same shovel for 32 years and have used straight 50 weight oil, now I'm not up on all of the additive stuff but those motors are way different than today's engines. From new that bike came with straight 50 and I stayed with it, now that motor has been apart many times over the years so I can't say that the straight oil was good or bad but sittin at idle when it's 85 plus you want as thick oil as you can in those motors. Try both grades see how the motor sounds see where the oil pressure is at and go from there. I always change my oil every couple thousand miles anyway a lot sooner than required. Have fun with the old girl.