Honda C70 Passport oil choices?

Messages
90
Location
Illinois
I have '81 and an '82 Honda C70's. I don't know alot about motorcycles, and can't find very specific information online about the oil in these bikes. The repair manual says to use Honda 4 stroke oil SAE 10w40 or equivalent. I realize these bikes are pretty tough and will probably run on just about anything, but being a typical BITOG member, I want to understand what will optimize the bikes' maintenance. My twin boys turn 16 in a couple weeks and will likely be running the stuffings out of these Hondas. Sorry if these questions are a little basic: 1. The bikes have a shifter and gears, but there is not a clutch and they shift like the old Honda 3-wheelers. Does this have a "shared sump" or "wet clutch"? Something different? 2. I used to just run Honda 4-stroke or synthetic PCMO in them, but switched to Mobil 1 Racing 4T motorcycle oil recently. Does motorcycle-specific oil add anything to this type of engine/transmission setup? 3. With a .8 qt sump, money is no object on oil for these two bikes. If you could choose any oil for these, what would you go with? (synthetic motorcycle oil, hdeo, etc) What grade? (10w40, 15w40, 5w40, 20w50) Brand? (Mobil 1, Valvoline, Amsoil, Rotella, Delo)? I would appreciate hearing the thoughts of the BITOG members on what oil I should run in these 40 year old classic Hondas.
 
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Messages
7,651
Location
The Midwest
Use 10W40 as specified. Mobil 1 Racing 4T works fine and is easier to obtain than Amsoil. How old are the tires and tubes on those Hondas? I assume you already know you need insurance on a moped and scooter in Illinois. Electric bikes don't need them in Illinois however.
 

zstand

Thread starter
Messages
90
Location
Illinois
I put news tires on them last year. Yes, I have owned them since the early 90's (paid an old farmer $180 & $200, respectively, for them), and have had them licensed and insured off and on.
 
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Messages
26,415
Location
PNW
I'd just use Valvoline 4-cycle 10W-40 (non-synthetic) - plenty good for those bikes. You can get it at Walmart for around $4.50 a quart.
 
Messages
10,469
Location
Jupiter, Florida
Either of the above oils will work fine. The clutch is a wet clutch with a centrifugal component. If you press on the shifter partially, you will probably find the clutch disengages. Yes, a quality motorcycle oil will handle the heat of an air cooled engine better, and will resist shear. The M1 product is top notch.
 
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Messages
1,448
Location
Ca USA
Honda owners manual recommends 30 grade... either one of the above brands in a synthetic or mineral oil will meet and exceed your mileage expectations... [Linked Image]
 
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Messages
937
Location
Colorado, USA
Originally Posted by BusyLittleShop
Honda owners manual recommends 30 grade... either one of the above brands in a synthetic or mineral oil will meet and exceed your mileage expectations... [Linked Image]
What C70 manual did you get that from? The continual misinformation you post BLS is laughable. 10w30 us NOT recommended as a catch-all oil, nor would I have run 10w30 oil in 100° Fahrenheit Midwest summer temperatures when I owned a C70 back in the early 80s, because it is outside of the upper temperature range for that oil according to the manual. It is very clear Honda recommends a 10w40 for all around use. This is from an actual C70 user guide, I let the C70 reference be seen for veracity, seems to be needed. Hard to see but 20w40, 10w40 or 10w30 based on temperature. [Linked Image]
 
Messages
6
Location
GA
I have 2 CT70's, one is an auto clutch 3 speed with an 85cc big bore kit, and the other is a manual clutch 4 speed. I run either Delvac or Rotella in 15w-40 weight. I also run this in my XR200, XL200, and XL600. Works great in all of these. Smooth shifting, no clutch slippage, and about 1/3 the price of "motorcycle oils". I also use in the transmission of my KDX200 with great results.
 
Messages
937
Location
Colorado, USA
That's good common sense oil selection. I didn't know they came with anything but the auto clutch 3 speed! Must have been in earlier version?
 
Messages
26,415
Location
PNW
Originally Posted by Bonz
[It is very clear Honda recommends a 10w40 for all around use.
10W-40 works well in about every motorcycle ever made ... probably the most specified oil viscosity for the last 50 years.
 
Messages
2,512
Location
Deep in the heart of Jersey
Originally Posted by ZeeOSix
Originally Posted by Bonz
[It is very clear Honda recommends a 10w40 for all around use.
10W-40 works well in about every motorcycle ever made ... probably the most specified oil viscosity for the last 50 years.
Uh, maybe every water cooled honda ever made.,,,
 
Messages
26,415
Location
PNW
Originally Posted by BigCahuna
Originally Posted by ZeeOSix
Originally Posted by Bonz
[It is very clear Honda recommends a 10w40 for all around use.
10W-40 works well in about every motorcycle ever made ... probably the most specified oil viscosity for the last 50 years.
Uh, maybe every water cooled honda ever made.,,,
Nah ... even air cooled big 4-cycle bikes in the 70s (ie, Kawasaki Z1 900) had 10W-40 as a viscosity option. Look at the page marked 163 in the PDF linked below. http://classickawasaki.se/Tekndokument/KawasakiFoursRepairGuide-En%5B1%5D.pdf
 
Messages
1,448
Location
Ca USA
Originally Posted by Bonz
It is very clear Honda recommends a 10w40 for all around use.
True but Honda gives the owner the choice between a 30 and 40 grade... either choice will meet and exceed your mileage expectations...
 
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Messages
937
Location
Colorado, USA
Originally Posted by BusyLittleShop
Honda owners manual recommends 30 grade... either one of the above brands in a synthetic or mineral oil will meet and exceed your mileage expectations... [Linked Image]
Here is your post BLS. I just don't believe how you sling stuff out there. Honda does not recommend a 30 weight, they recommend a 10 w40. BLS, I was going by YOUR post stating that Honda was recommending a straight 30 weight or a multi weight 30 weight as the heaviest oil for the C70. You specifically said Honda recommends that. You made no mention of a 40 weight and your illustration does not show a 40 wt. To most folks it's clear you we're saying this was a gospel truth recommendation from Honda by posting an illustration with your words. Nobody's putting a lick of stock in what you say. You put stuff out there that is not accurate in the least, is outdated info in many cases and does nothing to help anyone coming to the site for the first time like you have claimed it does in other threads. Really enjoy the story about that awesome bike you have, but the rest of it just seems like talk for the sake of talk and not any substance behind it.
 
Messages
1,448
Location
Ca USA
Originally Posted by Bonz
Really enjoy the story about that awesome bike you have, but the rest of it just seems like talk for the sake of talk and not any substance behind it.
I appreciate your candor...
 
Messages
1
Came across this thread while searching what oil to use for the bike. I was surprised that it wrote SAE30 on the bike and even SAE20 if under colder climate.
So, which should I use? The bike starts just fine but runs a little rough like any other c70 out there I guess?

Attached the photo I took from the bike engine cover
 

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Messages
26,415
Location
PNW
Came across this thread while searching what oil to use for the bike. I was surprised that it wrote SAE30 on the bike and even SAE20 if under colder climate.
So, which should I use? The bike starts just fine but runs a little rough like any other c70 out there I guess?

Attached the photo I took from the bike engine cover

Looks like the markings on the engine case match the chart posted in Post #6. As noted there, I'd just use a good 10W-30 to cover the entire temperature range.
 
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