WOW!, not good. Hope they got it fixed this last go around. First TG I've heard of sumping. Thanks for the heads up. I may go ahead and install the S&S oil pump and cam plate I've had for a couple weeks.

How many miles on it when it sumped?

 

Not sure if you know this or not but the way the oil is routed is important. You need the hottest oil coming from the engine to go to the Oil Filter. Once through the filter, off to the oil cooler then back into the engine. The hotter the oil, the easier it is to filter and keep the restrictions down. A better way would be to install a thermostat in the oil line prior to the cooler. This would allow the oil to return to the engine when cool without passing through the cooler. The coolers adds restriction due to there design and the fact that the oil gets thicker as it's cooled adds more. So a thermostat that bypasses the cooler when temperatures are down takes away those restrictions from the system.

As for adding the Oil Cooled version of the pump I do not know as it may be too much for the Twin Cooled version. It will however bolt right in place.

 

Spoke with the guys at fueling long before pumps were available for twin cooled bikes. They said because pumps for oil cooled bikes are such high volume, installing one in a twin cooled bike would cause sumping by overwhelming the the ability of their pump to scavenge correctly. I'll admit that I dont completely understand all the aspects of how that would happen, but I trust what they're saying.

 

Thanks, I rechecked the routing and it is correct. I do not have a thermostat in the system unless there is one at the area of the old filter location. (Front of engine) I think HD has an adapter with a thermostat installed. Will try to check that out and maybe change out the adapter. I've had the S&S oil pump and cam plate for a couple of weeks. Will probably go ahead and install those, just in case.....

 

I've got a 2021 RG Ltd 114 ci. I've been concerned that even with Amsoil, after 4-5 k mi on the oil, it seems like the cold startup is a bit nosier than when the oil is new. I've had no issues and I do use 20% Lucas Stabilizer in the engine oil change (one quart). With stabilizer, the noise at startup is non existent until the oil has lots of miles just prior to change. DK Customs and Mr. Clarke's Oil Bud both make oil coolers for twin cooled M8's. The DK Custom's require an oil filter re-location and the cooler sits in front of the left side lower vent (which you should never close unless it's freezing outside). The Oil Bud goes under the engine between the frame tubes and I prefer that configuration for three reasons; (1) doesn't block the left side lower fairing vent (2) less additional piping and potential pressure drop and flow issues and (3) it looks better in that you don't see it. Both have thermostats and the Oil Bud forces you to use a cleanable filter (not a problem except the initial cost). Thermostats open at just over 180 F and that's sufficient to get any trace water out of the oil.
Harley did not put an oil cooler on the twin cooled. Why? They believed, perhaps influenced by cost, that it didn't need it. I think that is technically true, but it irks me in that the oil temp at an ambient temp of 102 F and 90% humidity after one hour at 75 mph is 255 F. In moving traffic (stop lights) after that, with the radiator fans running, it drops to 245 F. With old conventional non-synthetic oil per Motor Trend experts, conventional oil starts to break down at 250 F. Synthetic, particularly high quality like Amsoil, can handle 300 F. There is an Amsoil, Harley of course, test at 300 F for 1000 miles and it didn't fail (Youtube). Your cars, your liquid cooled Indians and Goldwings, won't see oil temperatures above 210 F.....ever. So Harley engineers, as always, take it right to the edge for aesthetics and cost. They could have designed an oil cooler for the twin cooled with proper screwed hoses (not clamps), with a thermostat and located it above the water pump or underneath between the frame tubes and kept the oil reservoir below say 225 F if not a bit lower. That would ensure the oil would be in better shape on average before oil changes.
So, I'm still thinking about adding one, but the comment in this thread on Harley putting a lower volume output oil pump in the twin cooled worries me when adding lines and an oil cooler regardless of which one above. So more checking needed there. Will the bike go 50+ K miles without one, probably. But--keep the vents open and change that oil on time every time. Use the best oil and remember Syn 3 is about 40% non synthetic or conventional and is made by CITGO (not on par with Exxon (Mobil 1) or Shell (Penzoil Ultimate).

 

I won`t even attempt reading that wall of text.

 

You worry too much and prolly don't ride alot because of it...

 

Unfortunately at 102 deg F after 1 hour at 75 mph my 2021 RG Ltd twin cooled hits 254 deg F oil temp per the Harley digital dipstick temp gauge. This is not great and right up to the design limit for quality synthetic motor oil and above the design limit for conventional oil. It's not clear, but the oil pump on the M8 has a different discharge gear part number--it might be smaller with lower capacity than a regular oil cooler equipped M8. Makes picking one of the three available oil coolers for twin cooled M8 concerning (extra piping).