[JessHerbst]

I never realized just how regional oil companies are until this post.
 Seriously, the only oil brands mentioned here that I have heard of in Texas are Mobile & Castrol.
 

[biscot]

Castrol Power1 Racing 10W50 full synthetic.
That's what my dealer uses, and it's what I've been using for 30,000 miles on my Interceptor. I get it from Amazon for about $8 per quart free shipping in USA. I change oil and filter (OEM from ebay) every 3000 miles just for fun.

[morganwood70]

I'm using penrite 15w-50 full synthetic. I'm in Aussie so it doesn't get too cold here...

[gizzo]

Ghee.

[anglojaxon]

I used Lucas 10W50 full synthetic that's JASO and MA-2 compliant for "wet clutches." 4 quarts at around $49. As long as it meets requirements it's good. Prolly not good on salads.

Silkolene, Motul seem to be the preferred oils. They are pricey. Maxima ProPlus seems to be another option.

[fireypete]

Tracker MC-4ST is a semi synth.  I was going to run that but it just happened super cheap had Castrol fully synth on sale.
Theories on what to run boil down to personal beliefs/opinions. 
I dare not express anything here, you know why. 

[whippers]

Tracker MC-4ST is a semi synth.  I was going to run that but it just happened super cheap had Castrol fully synth on sale.
Theories on what to run boil down to personal beliefs/opinions. 
I dare not express anything here, you know why.

Theories don’t. What matters is the manufacturers specification unless you don’t care about a warranty or assume you know more than Royal Enfield does

[hehehemann]

Castrol Power1 Racing 10W50 full synthetic.
That's what my dealer uses, and it's what I've been using for 30,000 miles on my Interceptor. I get it from Amazon for about $8 per quart free shipping in USA. I change oil and filter (OEM from ebay) every 3000 miles just for fun.

I'm about to do my 300 mile service myself and have a choice of three oils locally at decent prices.

The Castrol Power1 10w50 synthetic is what the local dealer uses
Maxima Pro Plus or the Motul 7100 are other choices I have. These two are ester based but does it really matter if they all meet MA2 and bike requirements.

Thinking I'll just go with the Castrol as its about the same price as the other two but gets me 2 extra quarts if I order on Amazon.

[Ton1959]

This one

[StefArmstg]

One of the  dealers here only stocks 15w50. I think the uce singles use the 15w50..  But twins should use 10w50.  I use Motul 7100.

[AH56]

Motul 7100 10W-50 (Amazon), 14x20x1.5mm copper crush washers (Amazon) and OEM filters (6-pack from India via eBay).  Working great!

[wtdfxsys]

I went to the RE dealership and to my surprised they gave me royal purple 20w-50, they told me they use this to all of their vehicle.

[Shifty1969]

Oil is like beer, its different all over the world, but it’s all still pretty good, I use the 5-w-50, gets into the top end quickly and with a good warm up makes everything nice and quiet!

[Ton1959]

I went to the RE dealership and to my surprised they gave me royal purple 20w-50, they told me they use this to all of their vehicle.

I suppose it all depends on the outside temperature. In my BMW manual it had a nice temperature chart too. That can help when you want to decide on your oil. I do always prefer synthetic though. I wouldnt put it in my previous R80 though as it could have caused  oil leaks. Old seals can develop oil leaks if you suddenly change over to synthetic.

[John Mullen]

I'm using Mobile One full synthetic 15/50 oil.  Same great product I've been using in all my bikes for 40 years.