Best synthetic oil for primary ?

38297 Views 43 Replies 32 Participants Last post by hoot51, Nov 28, 2007

Mark A. Nemetz

Discussion Starter · Aug 25, 2002

I converted my Dyna Wide Glide over to Mobil 1 "V-Twin" oil in last weekend. I also put the 70-90W Mobil 1 in the chain case. The problem is that I could not find any 10W40 Mobil 1. All I could see on the store shelves were 0W30, 5W30, and 20W50. I had heard that a lot of manufacturers stopped reccomending 10W40, so a lot of suppliers stopped stocking it. I did have a quart of Golden Spectro 10W40 semi-synthetic at home, which I heard was OK to use....so I used that. Anyone have any experience with Golden Spectro oils ?

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twincamzz

· #2 · Aug 25, 2002

Yep, I used to use Golden Spectro semi synthetic in my tranny (84 FXRS). Never had any problems, shifted smoooooth as silk.
twincamzz

JoeJitsu

· #3 · Aug 26, 2002

The Mobil 1 20W50 is great for V-Rods

Sidewalk

· #4 · Aug 26, 2002

What I got:

15w-50
75w-90

Mobil 1

BOOMER

· #5 · Aug 26, 2002

Redline MTL

Duoglide_62

· #6 · Aug 27, 2002 (Edited)

www.amsoil.com has a SAE 10w-40 motorcycle oil that you can run in your primary. You can also look @ www.bel-ray.com. They have a V Twin conversion guide that has all their products listed. You can also check out www.redlineoil.com. I believe they recommend their MTL. I was told that the 'top secret' motor co. primary fluid is plain old SAE 5W-30 refined by Shell or Sunoco.

One thing to keep in mind is that there are quite a few standards used to grade oils, lubes etc. For example, a 75W-90 gear lube has nearly the same viscosity as SAE 10w-40 motor oil. That's not to say that you should substitute one for the other. You should just be aware of the differences when choosing oils and the like so you don't get hosed by all the marketing hype.

Unome

· #7 · Aug 28, 2002

Maybe Hippo can help here.

Correct me if I'm wrong but isn't the primary similar to the differential in rear wheel drive cars? Both serve same function. I saw on another post where someone said you can run synthetic 75w90 in the primary. Now I'm not about to just do this and definitely ain't asking local h-d shop for opinion(already know what their response will be.

Hippo, you comments or anyone else?

thomas_l

· #8 · Aug 28, 2002

Unome said:
Correct me if I'm wrong but isn't the primary similar to the differential in rear wheel drive cars?

You're wrong.

The clutch is swimming in there along with the chain connecting the engine drive and the clutch hub. There's no gears meshing like in a differential.

I put Mobil 1 15w-50 in the engine but bought the magical H-D fluids for the primary and trans since the amount was so small and I didn't have time to research any alternates. I refuse to pay double for "V-twin oil" that is probably the same thing as the stuff I bought at K-mart for $3.99/qt. Sure I can afford it - I just hate being ripped off for $15 because its "specially blended for v-twins." Bull$hit.

The only worry I would have with dumping any 75w-90 in the primary case would be friction modifiers used in a regular gear lube causing unpredicatable clutch performance. Looking at the BelRay site, they have one product clearly labeled for gear assemblies only (gear saver hypoid gear oil) and another for primaries and transmissions (motorcycle transmission oil). The reports of 10w-40 motor oil going in the primary case agree with my eyeball guess of the HD primary oil - it is definitely not thick and stinky like gear lube. Next big service I do I am inclined to buy an extra quart of the 15w-50 motor oil and use that in the primary case while finding some syn 85w-140 lube for the trans.

Unless someone with a better experience posts here first

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G

· #9 · Aug 28, 2002

More idle musings from me with no actual experience to back it up...

Now that Mobil 1 has a new formulation with friction modifiers, I'd be hesitant to put it in the primary. I know that Jap bikes (with engine and clutch lubrication shared) can have clutch problems when using oil with friction modifiers. Doesn't bother me a bit to put the new Mobil 1 in the engine though ...

HIPPO

· #10 · Aug 29, 2002

The best primary oil is Redline MTL.

If you want to use something else, use a light gear oil with GL4 specs. By all means avoid the GL5 spec and even the GL4/GL5 spec.

Some aftermarket clutches require ATF.

miken488

· #11 · Sep 2, 2002

Mobil 1

I have used Mobil 1 oils for sometime now, both in my 95 Low Rider, and my new 2002 Road King. I started using Golden Spectro synthetics sometime ago, but switched to Mobil 1 about 4 years ago. The use of synthetics in your transmission will make it shift much smoother, and run quieter and cooler than with conventional HD transmission oil. It also lowers friction and has less horsepower loss due the increased flow of the synthetic oil. In fact, Amsoil advertises that mileage increases by 4% when using their synthetic transmission oil. The use of synthetic oil in the engine has lowered my engine oil temperatures by 12-15 degrees.

Mobil 1 now says that you can use their 20w-50 V-twin oil in the motor, the primary, and the transmission. The use of synthetics in the primary will extend clutch life, and lower temperatures. Even thought Mobil 1 says one oil will cover all 3 areas, I still use Mobil 1 synthetic 75 - 90w gear oil in my transmission, and the 20w-50 in the primary and engine.

Mike

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cornea

· #12 · Sep 7, 2002

Primary oil

Howdy all, I contacted mobil 1 on their web site. They advise using the MX4T 10w40 oil for the primary because it has no friction modifiers. I have not yet put it in the bike, but I'll do so this weekend. I will let you know how it works after a month or so. I am somewhat hesitant to use the gear oil in my primary. I use it in the tranny, but it sure feels thick to me for the primary. But what do I know?? Not much about oils.
adios,,

hd2000fxdl

· #13 · Sep 11, 2002

Hey Mark A Nemetz,

The reason you see all the new vehicles recomending 5-20 or lower is for the company to meet mileage spec's. I have 2 vehicles 99 and 02 along with a 00 Lowrider. I use 10-40 in the car and truck, just because I like it and it works fine, also it keeps the inside on my engine clean, so I go by the rule don't change it it's working good. On the HD I use hd oil 20-50 but change it every 1k. My rule of thum. I guess I change my oil enough and it's not dirty enought I might just start using it in my truck. Well it just a truck.

Sidewalk

· #14 · Sep 11, 2002

The 5w-20 is for emissions/mileage purposes. However, the engine tolerances have been tightened up as well. So you are going to get a lack of lubrication to these tighter tolerance bearings, additional wear will be seen over time.

The philosophy of "If it isn't broken, don't fix it" doesn't work when these things change.

chiselchst

· #15 · Sep 12, 2002

What I found very interesting was to do a search on this Forum, with the word "Synthetic".

paphigliano

· #16 · Sep 13, 2002

We have found for stock bikes any oil in the primary will work some better than others, but if you are a big bore boy or a stroker nut ;that the synthetic gear oils,,,,,75/90 really make the clutch hook up. I have built 110hsp motors and used the stock clutch spring as long as you use the 75/90 in the primary,,,,,,if you use 10/40 or 20/50 in the primary on these style of motors you will need to upgrade the clutch spring,,,,,,its the way it works around here for us anyways.

Texxen

· #17 · Sep 14, 2002

It's amazing how people contradict themselves when it comes to oil. They won't spend money on good quality oil but don't hesitate to buy Harley oil........

Markcuda

· #18 · Sep 14, 2002 (Edited)

I may be a idiot here but I think I will just stick with the Harley oil till I can sort all this oil thing out

I know there is oil that is just as good as the Harley stuff but the money thing is not going to matter, I will have 23 grand in mine before it even leaves the dealer, so I ain't going to buy cheep stuff

DMC

· #19 · Oct 31, 2004

paphigliano said:
We have found for stock bikes any oil in the primary will work some better than others, but if you are a big bore boy or a stroker nut ;that the synthetic gear oils,,,,,75/90 really make the clutch hook up. I have built 110hsp motors and used the stock clutch spring as long as you use the 75/90 in the primary,,,,,,if you use 10/40 or 20/50 in the primary on these style of motors you will need to upgrade the clutch spring,,,,,,its the way it works around here for us anyways.

That's quite interesting, I have deducted from reading these boards, that some guys are using Mobil1 75W/90W in their trannies, but this is the first time I've heard of it being used in the chain case/primary. Looks to me like the heavier gear oil will add life to a clutch period. What do you like in your tranny and crank case?

It would just be to damn easy for me to use Mobil1 15W/50W in the crankcase and Mobil1 75W/90W in both the primary and tranny.

I have been reading up on this quite a bit today, and being somewhat possessed by the need to understand oil, I study it quite a bit.

You being a engine builder/motor head, I'm sure you have read up a bit on this subject as well. I don't buy into HD's Recomendation of 20W/50W Syn for all three holes, Not in the best lubricant available for each application.

Thanks for sharing

Don

Mr. Z

· #20 · Oct 31, 2004

Red Line

I have researched this to death. I have found that what oil you like is like what religion you prefer. I was having a slight clutch grab using SYN3 and found lots of testimonials that said REDLINE MTL would fix it. These same riders and techs also recommended REDLINE shockproof heavy for the tranny and their 20/60 HD for the crank. I finally found all three and could not be happier. You will note that Hippo who has a great rep on this and other forums says MTL for the primary. I give him a big thumbs up on this. Solved my grab problem and the engine runs cooler than with the SYN 3 which is only about 60% syn.

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