Primary Oil: ATF vs Redline vs Motul vs Spectro Vs Bel Ray vs Lucas
HDF Community Team
Joined: Mar 2017
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From: Texas
Since the oil thread said no new post I wanted to get some opinions on the following primary oils with desired results etc.. As well as info I have gathered from experience and forums.
SIde note: I absolutely love motul engine oil and spectro gear oil for transmission. Both have performed amazing for me with wows when changing and running
I have 2 goals. So might use 2 different primary oils
First Bike; 2001 fxdxt with harley 120R engine with baker 6OD tranny. Has a Heavy duty diaphragm spring and a extra plate clutch pack with those weight aim pressure plate (will upgrading to barnett). Want a performance primary oil.
second and third bike 2001 fxdx, and 2001 fxdwg 2 CVO. Want a solid oil for longevity and something that protects compensator and chain.
ATF:
Used ATF Trick shift type F in a 1994 fxr that had a 130 ultima and barnett clutch. The oil was extremely thin clutch engagement was really good for a perfomance bike. I did not own it long enough to see how the compensator wear was.
My take is this fluid is very thin. Great for clutch engagement may not be the best for primary drivetrain wear.
should be around 7 cst @100C
lowest viscosity out of all primary fluids ive researched and used.
Redline:
Synthetic primary oil with a weight 5w30 (75w80 gear oil) and Vis @ 100°C 10.4 cst.
Seems nice and thin for good clutch engagement and enough viscosity to protect the chain and compensator.
Although I havent been the biggest fan of redline when i tried there gear oil.
People talk down about synthetics in the primary but this one was specially developed for it and not the engine
Motul Primary and chaincase oil:
Another synthetic that has a weight of 10w40 (85w gear oil)
Couldnt find any info on Vis @ 100°C but assuming its around 14-15 cst based on its weight
Again another synthetic specifically made for the primary. Thicker than the redline so may affect clutch engagement but should be good on the chain etc.
One thing Id like to say is the synthetics in theory should degrade less and protect the primary when riding in the desert (I live in socal so this could be a huge benefit). Obviously could just change the primary oil more often but id rather not.
Now on to conventional or semi synthetics
Spectro:
This chain case oil is a 85 weight gear oil and is most likely very similar to the motul synthetic primary fluid
Couldn't find the data but looks to be Vis @ 100°C but assuming its around 14-15 cst based on its weight.
Seems like another good choose with good clutch engagement and protecting the primary.
Also just seems like the same exact thing as the lucas primary oil (which is what is currently in all my bikes)
Only a couple dollars more than lucas....
LUCAS:
Cheap easy to find and has a Vis @ 100°C 14.44 cst. Most likely another 10w40 (85 gear oil)
One thing Ive noticed is after a few thousand miles and some hard riding this fluid smells bad and seems burnt and degraded.
Clutch engagement is nice. Good performing oil but nothing that is a wow. When I switched from amsoil to motul in the engine I noticed a huge difference in blow by and also how new the fluid still looked and smelled when I change it.
Bel Ray:
The lightest weight and lowest viscosity
80w gear oil Viscosity @ 100°C, 9.53 cst
The lowest CST besides ATF. Havent heard the best reviews on this.
IN theory should have the best clutch engagement and least wear protection on the primary parts
I have been researching this hard and long. OCD probably about something that really wont matter....but what are your opinions.
I know all the big clutch companies recommend ATF...might be the best for the clutch pack but what about all the other moving parts....
Thicker oil appears to give the less clutch perfomance...so its kind of like a trade off. IN the performance application go with lowest viscosity and for the bikes i want to run forever with no problems highest viscosity and synthetic??????? MAYBE EVEN SYNTHETIC 20w50...like motuls 7100 thats already in the engine....
For my T sport with the 120R i was thinking the following: With clutch performance at top of priority list
1. ATF Type F or Dexron ( Although i dont want to do this lol)
2. Redline
3. Bel Ray
4. Spectro
5. Motul
For my runners and garage queen:
1. Motul primary and chaincase oil
2.Spectro Primary oil
3.Lucas Primary Oil
Seems like one of those things where you cant have one if you have the other. Also when clutches are slipping (and clutch is in good shape/new) I am in the school of thought you need more pressure....so all things aside. Motul primary synthetic seems like a good between for performance and longetivity. While engine oil would provide the best protection but worse clutch performance. ATF will provide the best clutch performance but least protection.
On a side note. If you want to keep your life simple. Go with 1Maxima full line or 2Amsoil Full line and life will be good. Ive gotten good results from both but neither have blown me away.
Probably best to stick with one brand for the life of the bike. THis will probably give the best results in the long term and you get to spend more time riding and less time obsessing. But I am OCD and want to find those gems for each hole and so far I have found the following
Engine Oil: Motul 20w50 full synthetic. Broke my 120R in with this from the start based on MICKEY COHENS recommendation after he dyno tuned her. Told me to ride it like I stole it after the dyno run it was basically fully broken in. Just dont hit the rev limit @6200 till 500 miles were on. her. Cant say i listened but the bike purrrs and sounds amazing after 2000 miles zero issues.
Transmission Oil; Spectro has treated me well and I love how they have a gl-1 green dye tranny fluid for my harley original 5 speeds. Yes I know the current GL-5 are backwards compatible now but yea I am weird.
HELP me make a decision on something pointless yet i've been up for the last three days agonizing over this decision LOLOLOL
SIde note: I absolutely love motul engine oil and spectro gear oil for transmission. Both have performed amazing for me with wows when changing and running
I have 2 goals. So might use 2 different primary oils
First Bike; 2001 fxdxt with harley 120R engine with baker 6OD tranny. Has a Heavy duty diaphragm spring and a extra plate clutch pack with those weight aim pressure plate (will upgrading to barnett). Want a performance primary oil.
second and third bike 2001 fxdx, and 2001 fxdwg 2 CVO. Want a solid oil for longevity and something that protects compensator and chain.
ATF:
Used ATF Trick shift type F in a 1994 fxr that had a 130 ultima and barnett clutch. The oil was extremely thin clutch engagement was really good for a perfomance bike. I did not own it long enough to see how the compensator wear was.
My take is this fluid is very thin. Great for clutch engagement may not be the best for primary drivetrain wear.
should be around 7 cst @100C
lowest viscosity out of all primary fluids ive researched and used.
Redline:
Synthetic primary oil with a weight 5w30 (75w80 gear oil) and Vis @ 100°C 10.4 cst.
Seems nice and thin for good clutch engagement and enough viscosity to protect the chain and compensator.
Although I havent been the biggest fan of redline when i tried there gear oil.
People talk down about synthetics in the primary but this one was specially developed for it and not the engine
Motul Primary and chaincase oil:
Another synthetic that has a weight of 10w40 (85w gear oil)
Couldnt find any info on Vis @ 100°C but assuming its around 14-15 cst based on its weight
Again another synthetic specifically made for the primary. Thicker than the redline so may affect clutch engagement but should be good on the chain etc.
One thing Id like to say is the synthetics in theory should degrade less and protect the primary when riding in the desert (I live in socal so this could be a huge benefit). Obviously could just change the primary oil more often but id rather not.
Now on to conventional or semi synthetics
Spectro:
This chain case oil is a 85 weight gear oil and is most likely very similar to the motul synthetic primary fluid
Couldn't find the data but looks to be Vis @ 100°C but assuming its around 14-15 cst based on its weight.
Seems like another good choose with good clutch engagement and protecting the primary.
Also just seems like the same exact thing as the lucas primary oil (which is what is currently in all my bikes)
Only a couple dollars more than lucas....
LUCAS:
Cheap easy to find and has a Vis @ 100°C 14.44 cst. Most likely another 10w40 (85 gear oil)
One thing Ive noticed is after a few thousand miles and some hard riding this fluid smells bad and seems burnt and degraded.
Clutch engagement is nice. Good performing oil but nothing that is a wow. When I switched from amsoil to motul in the engine I noticed a huge difference in blow by and also how new the fluid still looked and smelled when I change it.
Bel Ray:
The lightest weight and lowest viscosity
80w gear oil Viscosity @ 100°C, 9.53 cst
The lowest CST besides ATF. Havent heard the best reviews on this.
IN theory should have the best clutch engagement and least wear protection on the primary parts
I have been researching this hard and long. OCD probably about something that really wont matter....but what are your opinions.
I know all the big clutch companies recommend ATF...might be the best for the clutch pack but what about all the other moving parts....
Thicker oil appears to give the less clutch perfomance...so its kind of like a trade off. IN the performance application go with lowest viscosity and for the bikes i want to run forever with no problems highest viscosity and synthetic??????? MAYBE EVEN SYNTHETIC 20w50...like motuls 7100 thats already in the engine....
For my T sport with the 120R i was thinking the following: With clutch performance at top of priority list
1. ATF Type F or Dexron ( Although i dont want to do this lol)
2. Redline
3. Bel Ray
4. Spectro
5. Motul
For my runners and garage queen:
1. Motul primary and chaincase oil
2.Spectro Primary oil
3.Lucas Primary Oil
Seems like one of those things where you cant have one if you have the other. Also when clutches are slipping (and clutch is in good shape/new) I am in the school of thought you need more pressure....so all things aside. Motul primary synthetic seems like a good between for performance and longetivity. While engine oil would provide the best protection but worse clutch performance. ATF will provide the best clutch performance but least protection.
On a side note. If you want to keep your life simple. Go with 1Maxima full line or 2Amsoil Full line and life will be good. Ive gotten good results from both but neither have blown me away.
Probably best to stick with one brand for the life of the bike. THis will probably give the best results in the long term and you get to spend more time riding and less time obsessing. But I am OCD and want to find those gems for each hole and so far I have found the following
Engine Oil: Motul 20w50 full synthetic. Broke my 120R in with this from the start based on MICKEY COHENS recommendation after he dyno tuned her. Told me to ride it like I stole it after the dyno run it was basically fully broken in. Just dont hit the rev limit @6200 till 500 miles were on. her. Cant say i listened but the bike purrrs and sounds amazing after 2000 miles zero issues.
Transmission Oil; Spectro has treated me well and I love how they have a gl-1 green dye tranny fluid for my harley original 5 speeds. Yes I know the current GL-5 are backwards compatible now but yea I am weird.
HELP me make a decision on something pointless yet i've been up for the last three days agonizing over this decision LOLOLOL
- Choose the oil that the manufacturer recommends
- Don't do #1
- Choose the correct viscosity (per the manufacturer and OPERATING conditions) - this is the single most important aspect of lubrication selection
- Choose oils with the correct additive packages
- Engines need engine oil as they need dispersant packages to collect the soot particles and get them to the oil filter. Nothing but engine oil in the engine.
- Transmissions and primaries can use gear or engine oil. BASE OILS ARE THE SAME BETWEEN ENGINE AND GEAR OILS - ONLY THE ADDITIVES ARE DIFFERENT.
- Engine oils contain about 25% additives. Gear oils are about 10% additives. ATFs contain up to 30% additives.
- The additional additives within engine oil are not harmful to the transmission or its performance.
- NEVER USE EXTREME PRESSURE ADDITIVES (E.G., HYPOID GEAR OIL, GL-5) IN A WET CLUTCH PRIMARY OR WHERE THERE ARE SOFT/YELLOW METALS
- Soft/yellow metals will corrode and clutches may slip
- Many ATFs contain EP additives. Be very careful in your selection.
- ATF: Don't assume that because it is "thin" that it has less "protection" than "thicker" oils. ATF includes a LOT of friction modifiers (meaning the oil sticks to surfaces more than oils without the friction modifiers). Sticking to surfaces is the optimal condition and is why "thicker" oils prevent more wear than "thinner" oils. ATF can provide the same "protection" with lower viscosity than a "thicker" oil with a higher viscosity.
Temperature. You need to know your operating temperature. Your transmission and primary are not getting to 100*C, so using that datapoint is not accurate. Viscosities are not linear. You need to perform a Reynolds calculation for interpolating viscosity at the correct operating temperature. There are online calculators for that. Like this: Viscosity-Temperature Calculation (tribology-abc.com)
If you're wanting the highest possible "performance" at all costs, you get the absolute thinnest oil possible to 1) reduce the amount of drag that the internals face and 2) prevent catastrophic wear for the duration you deem acceptable. Whatever "performance" means. If you're drag racing professionally, you may only need oil for one run down the strip. You run extremely thin oil and boundary condition tolerances, then dump the oil and rebuild certain aspects of the engine to account for that wear. If you're wanting an oil to last 5,000 miles, you want an oil that will retain its viscosity for that mileage.
Synthetic vs. Dino: Synthetic base stocks hold their viscosity longer than dino base stocks. There are other differences, but not worth mentioning.
Smell: oil smells like oil. Funky smells are additives. They tell you nothing about the age of the oil. Yes, the smell changes through heat cycles and with contaminants, but don't base the life of the oil off of smell. If it smells like sulfur, don't put it in the primary - sulfur is an EP additive. See note about EP additives above.
\Synthetic primary oil with a weight 5w30 (75w80 gear oil) and Vis @ 100°C 10.4 cst.
5W engine oil is LESS than 75W gear oil. There is no gear oil similar to a 5W engine oil; although, if there was it would be a 70W.
30W engine oil spans both 80W and 85W gear oil.
MOTUL
Another synthetic that has a weight of 10w40 (85w gear oil)
Couldnt find any info on Vis @ 100°C but assuming its around 14-15 cst based on its weight
MOTUL
Another synthetic that has a weight of 10w40 (85w gear oil)
Couldnt find any info on Vis @ 100°C but assuming its around 14-15 cst based on its weight
Also, BIG ASSumption. There are major brands of oil that have a 20% variance in viscosity between each other and are rated the same weight. SAE allows for a 20% variance in viscosity for classification, meaning a 40W should be 12-18 cSt @100*C, yet could be 10-22 cSt and STILL be classified as a 40W.
If you made it this far, congratulations. Bottom line: pick an appropriate oil and ride. You have already wasted more time than the amount of money you'd ever save or enjoyment you'd have riding.
Seasoned HDF Member
Joined: May 2008
Posts: 20,836
Likes: 12,330
From: South Carolina
And now we are stuck with this garbage in every section of the forum.
Tourer
Joined: Jan 2021
Posts: 487
Likes: 269
From: Arizona
I like oil threads. I get it. I want the best oil I can get. It seems like the top name brands are all pretty good and you can't go wrong with any of them. It's fun to obsess about. I really liked what Brandon had to say that was informative!
Seasoned HDF Member
Joined: Aug 2008
Posts: 5,034
Likes: 981
your dollar and your machine.
every oil is mfg to a specific need. BUT you MUST be careful!!!!
WHY???
not all oil plays nice with all components. for ex: oils with a sulfur content will not play nice with the PMG. a famous hd racer once said: "if in doubt, do as the factory did" !!!
every oil is mfg to a specific need. BUT you MUST be careful!!!!
WHY???
not all oil plays nice with all components. for ex: oils with a sulfur content will not play nice with the PMG. a famous hd racer once said: "if in doubt, do as the factory did" !!!
Stellar HDF Member
Joined: Mar 2008
Posts: 2,328
Likes: 2,205
Because if you're stuck at work instead of riding, it gives you something to worry about.
