Synthetic oil and engine noise

08heritage67 · #1 05-07-2008, 09:48 PM

I have an 08 heritage and at the first service switched toHD synthetic. top side engine noise has increased, over that of my wife's 08 street bob and other HD bikes I ride with. I spoke to the HD mechanic and told him of the increased noise and his first question was if I had switched to Synthetic oil? He followed up by saying the the synthetic oil has smaller molicules to break apart and come together faster for engine protection and performance, however it does not dampen engine noise as much as "conventional" oil because the molecules are larger. Any truth? thanks for any feed back.

pococj · #2 05-07-2008, 11:12 PM

Nope, at least not for the explanation he gave. Synthetic oils are long-chain molecules, while dino oils consist of both long-chain and short-chain molecules. Long-chain molecules are why synthetic oils maintain their viscosity much longer than conventional oils.

But all of that doesn't explain why some engines seem to be noisier with certain synthetics.

Road King Craig · #3 05-13-2008, 01:24 PM

O8-67,
I just had my Oils changed at my 1000 mile warranty service for my 08 RKC, I went with Amsoil75-90svg for the tranny, and Amsoil 25-50 in the other, Instantly runs Quieter and very noticable to boot, shifts smoother AND QUITERtoo !. I have used Amsoil in all my dirt bikes and atvs over the last 20 years Its the best damn syn-Oil there is period ! Of course thats my Opinion.
Tj

Lost1 · #4 05-13-2008, 04:02 PM

Each engine or gearbox will sound different depending on what oil you put in it. I've had HD dino, Syn3, Amsoil, Redline, and Mobil 1 in my engine and so far HD dino & Syn3 have been the quietest, with M1 and Amsoil being the noisiest.
My transmission has had H-D Formula+, Amsoil SVG, Redline Shockproof, and Spectro Platinum 6-speed gear oil. (Tried different kinds to try & quiet the 5th gear whine.) Quietest was Formula+ and noisiest was Amsoil.

Put "X" brand oil in 100 engines or trannies and you'll get 100 different opinions on how it sounds...

KBFXDLI · #5 05-13-2008, 10:06 PM

SYn3 made my engine clatter. Went to Mobil1Vtwin...less noise but still some. Going to try Redline next. FWIW Amsoil 20w50 has the highest viscosity level of all of the 20w50 synthetic oils. But I get all my oil on sale or I don't buy it. I don't really think any of them make much noise difference. I just use synthetics because of the heat range protection. If dino protected past 250F I would definitely use that if it were cheaper. But I got a whole bunch of redline cheapwhen Advance Auto discontinued it. So that's what I'm using.

damnitj · #6 05-14-2008, 06:15 PM

I can only speak to my experience, and when I put in Mobile 1 15 50 after running dino, my scoot was noticeably noiser, even with 75-90 M1 synthetic gear oil. My present scoot has always had dino and hd products in it and seems to be quiet. Go figure.

big cahuna · #7 05-15-2008, 08:19 AM

I don't get it either. synthetic oils are supposed to be the best products for your bike, but after using dino oil and trying mobil 1 v twin, and Amsoil I can hear every tick tap and click the motor can make.just yesterday I was out air temp was around 80. riding around town, and some highway the noise would make you wonder if something was wrong with the motor. never had that with dino oil. I checked oil temp with gauge and it said 207 f. the oil looked clean but would drip off the dipstick like water. I'm thinking about going back to dino oil seeing that 207 degrees isn't that hot for a twin cam, and doing the 2500 mile changes. that would be about 3 a year for me.if anything I won't be going nuts hearing noises.

1FLTRI4ME · #8 05-17-2008, 08:25 AM

I've been using Amsoil for the last 20,000 miles.With 24,000 miles on the clock,I will be servicing the bike soon.My engine is pretty noisey.The local HD service writer test road the bike because of my complaint.He said the noise is normal.
I'm considering going back to HD dino oil just to see if it decreases the noise.

Knightlimper · #9 05-24-2008, 07:16 AM

Posted this in another thread, but its relevant here as well. Have been using the Red Line 20W60 for the last 5K miles on my Heritage. I live in Florida so the temps are now in the 90's, figured the oil might help with heat issues. Originally changed to the Red Line at 500 miles, I can say that the engine is quieter than when I had the break in oil. I know, I'm supposed to have 3K+ miles before switching but didn't wait, summer was here.

For curiosity I had a used oil analysis done on the first Red Line oil change (Changed oil at 4300mi), I was mainly interested in finding out when I should be changing the oil for the way I ride. I commute 80 miles roundtrip, mix of highway/city traffic. Engine does get hot when sitting in traffic, but I believe the oil is helping a lot.

Analysis came back showing oil can be stretched to 5,500 miles between changes based on how much additive remained in my 4,300 mile sample. Won't be stretching it that far, will go 5K between changes for now. Analysis also showed indicators of high wear (compared to normal levels) since I didn't wait 3K+ miles for the engine break in to be done before switching oil to synthetic. Got better engine temps in the heat of the summer, but will now have to watch the wear indicators in the oil analysis for a while. Oh well, guess they knew what they were talking about.

Bottom line is the 20W60 appears to be working great for me but all I have to compare with is the original break in oil.

twiceretired · #10 05-24-2008, 11:22 PM

Feel free to climb up my a$$ here if I got this wrong, but I always thought the 'theory' of not using syn during break in was to allow metal parts to wear together. That should result in identifiable wear particles in the UOA. So how does this statement: {Analysis also showed indicators of high wear (compared to normal levels) since I didn't wait 3K+ miles for the engine break in to be done before switching oil to synthetic.} make any sense?