I have a 1994 FXDS 1340 that is stage 3 with a big bore. I have had it for a short time and need to change the oil again. I used Harley 20-50 the first time. I'm wondering about changing to a synthetic blend or full synthetic for the engine oil. The bike was built before synthetics were used as much as now days. I live in central Cali where the temps are on the rise for the summer. Should I change oil type or just go with the conventional oil that's in it? Castrol, Mobil 1, Valvoline?
What do you guys recommend?

Thanks

 

More info here in the HDF Oil section;

https://www.hdforums.com/forum/oil-a...ted-topics-30/

,,, where I'm sure your answer is thoroughly covered.

 

That subject has been done to death in here! As you yourself remark, your bike dates before synth became used widely and I for one wouldn't use it. Stay with quality brands of suitable dyno oil. Check your owners manual or FSM, where I suspect you will find we should use a diesel lube for the engine, in the absence of the factory recommended stuff. You may be able to download the owners manual from the H-D website, go to the Owners tab.

 

Valvoline Racing (non-synthetic) 20w-50 is a good one for an evo. YD