I have a freshly rebuilt 76 RD400 motor completely stock. What's the most used gear oil for regular use, not racing ??
I'm planning to start it with premix and then check the pump to make sure it is in specs.
Is it 4oz of oil to the gallon ?
Thanks.
4 Oz are a gallon is 32:1 which is ok. heavy but safe. I run modern 4 stroke synthetic 10w40 motorcycle in the trans for wet clutch transmission (castrol).
I also run honda gn2 injection and pre-mix oil
prob the least common combo.
those
I use Yamaha 2S for injector oil and 10W30 or 10W40 Dino oil for transmissions.
Using Motul 710 for injector oil and Motul Transoil Expert in the trans.
The Transoil Expert did improve the shifting of my Derbi over regular oil.
Oh boy an oil thread! :celebrate: And it's even better because it's a double dose!
I've been using Motul 710 in all my 2-strokes for many years.
For trans oil it's Bel-Ray Gear Saver 80w.
Let start a poll.
Bel-Ray SI-7 Synthetic injector oil.
Bel-Ray Gear Saver 80w.
Yamaha 2S in the tank and Bel Ray Gear saver 80W in the case.
Motul 710 or BRP XPS 2T in the injector tank
Shell Rotella T4, T5 or T6 in the gearbox
I used to use T4 for everything, but now I have more modern bikes and mostly use T6.
Yamaha 2s and BelRay Gear Saver 80w in both bikes as well.
I'll also add I use BelRay fork oil too lol.
Here we go again.
I run 2 stroke oil from Action, semi synthetic. 5€ per liter and flawless over 10k km's of hard driving on my 2 strokes. Also use their car 10w40 in my gear boxes, never had a problem in any of my classic and modern bikes.
lesson to be learned here:
anything modern and intended for purpose..... is just fine. :toot:
Yamalube 2S in tank, 2R for premix, 4 stroke oil in gearcase
maybe I'm a blockhead, but I fail to see how running anything other than gear oil weight/viscosities recommended by Yamaha is helpful for 50+ year old 2 stroke engines. Newer isn't always better.
I run the modern 4t oils because they are better lubricators, designed to deal with way more hp and clutch abuse. and readily available in synthetic form. 10w30 vs 10w40 isn't a significant change. ive tried boutique oils, and ive killed two rd transmission on belray gear saver. never again. for me. but as far as oils go.. I have to disagree. newer is usually better.
Thanks to all that replied with their choices.
Didn't mean to start an oil thread or poll, but I can see where everyone is proud of what they have chosen and use.
I'll see what's available around in my cycle shops and go from there.
Appreciate the input.
im not proud or brand committed for sure. but everyone's preference works for them
I've seen it claimed in more than 1 place that full synthetic is "too slippery" for our old clutches. Same used to be said for ATF which was really popular in dirt bikes back in the 1970s. Some oils specifically are recommended for "high mileage" engines. Ford has recommended semi synth for decades. Anybody have any test articles confirming a clear winner between old dinosaur oil vs newer tech synthetics?
clutches are clutches (wet). no one's running full fiber discs these days, and the 4t motorcycle oil is made for wet clutches. so doesn't apply. maybe if you were running automotive mobile 1 or something w friction modifiers.. sure. but thats not the case
One change that has occurred to oil is the reduction of additives like ZDDP (Zinc and Phosphorus) that protect high pressure valvetrain parts like cams/lifters/rockers from damage in certain conditions.
Back in the day, regular auto oils were fine for cycle engines. Currently, regular auto oils are no longer safe. Diesel oils don't have the same restrictions, so they still have adequate levels of ZDDP.
That's why a lot of people run a diesel oil like Rotella.
Anything a conventional oil can do - a synthetic oil can do better. Synthetics flow better in cold weather and won't breakdown with extreme heat like conventional oils do. Their closed molecular structure makes them stronger and more resistant to oxidation.
EDIT: For 2-stroke trans oil, I don't believe ZDDP levels will matter, as it's mainly protection for high pressure contact surfaces found in the valvetrain. Friction Modifiers aren't an issue for the most part, as they are only used in oils under 40-grade,
very true.. but only really'flat tappet' cams issue mostly. really not a big issue on the Japanese stuff, tbh. at least ive never ever seen an issue on a dohc shim and bucket setup.ive seen a few v8 cams get wiped out tho. :huh:
Quote from: m in sc on February 13, 2026, 04:04:01 PMvery true.. but only really'flat tappet' cams issue mostly. really not a big issue on the Japanese stuff, tbh. at least ive never ever seen an issue on a dohc shim and bucket setup.ive seen a few v8 cams get wiped out tho. :huh:
As I understand it, you want the higher levels of ZDDP on any non-roller cam valvetrain.
Quote from: JKV45 on February 13, 2026, 04:09:12 PMQuote from: m in sc on February 13, 2026, 04:04:01 PMvery true.. but only really'flat tappet' cams issue mostly. really not a big issue on the Japanese stuff, tbh. at least ive never ever seen an issue on a dohc shim and bucket setup.ive seen a few v8 cams get wiped out tho. :huh:
As I understand it, you want the higher levels of ZDDP on any non-roller cam valvetrain.
Yup. I use high ZDDP Valvoline VR-1 in my Porsche, although Rotella has adequate levels of zinc too.
Quote from: JKV45 on February 13, 2026, 04:09:12 PMAs I understand it, you want the higher levels of ZDDP on any non-roller cam valvetrain.
You WANT about 1100-1200 PPM ZDDP. Too much ZDDP is a BAD thing.
Most motorcycle oils have about that level of ZDDP, any car oil advertising elevated ZDDP levels should have that much ZDDP. "Normal" car oil has about 800-900 PPM. ZDDP clogs car cat converters.
ZDDP is a lubricant of "last resort", if all else fails, there's still ZDDP... or boron or .... The idea is if you wipe all the oil off a metal surface (run out of oil), there is still a coat of ZDDP. You don't WANT to use the ZDDP... but it coats all metal surfaces, not just cam followers, mains and big ends too.
ZDDP is not the be all and end all of oil choices.
And the two things that have changed the most since these bikes were built is oil and tires. When these bikes were built; there was no "gear lube" and they were designed to use Reg 30 oil in the trans, not because it was GOOD, but because it was available everywhere. Gear lube is BETTER... you can build a gear lube with more sheer and less lubricity than a motor oil, that works better in a transmission.
IF you are going to run gear lube: you MUST use GL4, nothing else (use GL3 if you can find it, but GL3 was superseded by GL4). GL4 has lower levels of sulfur, the bright metal in the trans doesn't like sulfur. So no GL4/GL5... must be GL4.
Viscosity is rated differently in gear lube than motor oil... so a 75-80 gear lube is about the same viscosity as a reg 30 motor oil... about.
I will throw my hat in the ring. I use Lucas 80/90 in all my 2 stroke transmissions with good results over many years of hard street miles. I was a Klotz man for both premix and injector oil for many years and loved it until my research indicated that it contains little to no corrosion inhibitors and my bikes set a lot.
I switched to Blue Marble oil for years also with great results. Recently it has become unavailable. Now I am running Lucas semi-synthetic. It is reasonable in price and available locally. I am of the opinion that almost all of modern 2 stroke oils are superior to what our 2 strokes were designed to run on.
Thanks for ending another oil thread
For vintage motorcycles I don't think it matters much. The gearboxes are overbuilt and even in fairly extreme trim oil isn't the weak point for either engine or transmission performance.
For our race cars we've run some extremely exotic oils. Some worked and some didn't and I've seen a few transmissions bite it. I personally did one in for the tune $10k. Different problems can arise when you are doing dry sump and even dry sump transmissions. These aren't problems these old bikes have. Put oil in them and they are likely to work.
Quote from: m in sc on February 13, 2026, 11:02:14 AMim not proud or brand committed for sure. but everyone's preference works for them
THIS RIGHT HERE! I have read dozens of oil threads on car and bike forums over the years. And my take-away is that in most non-specialized applications, most modern oils are just fine for our dinosaurs who, by the way, fared pretty well with the far inferior oils (by today's standards) available during most of their lives. Which is why there is always LOTS of positive recommendations for a myriad of different oils. It's because ALL of the major oils work just fine for the typical, non specialized application.
Personally, I use YamahaLube. Not because I think it is the best. But because it is not expensive, is readily available, and has never caused any kind of issue. I run it in my Enduro and my RD and have run it in all my Yamahas forever (meaning decades). How much better than that can you get by spending more money or going to more difficulties in acquiring your oil?
:twocents:
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In my cars I use Mobil1 Synthetic.
on the 2 Yamahas, a 1979 XS1100 F and a 2015 VStar 950 Tourer, I use Yamalube. If not for the only reason that if they warranty their new bikes for 3 years, their oil must be good enough.
BelRay Gear Saver 80W has given me the best results out of all the various oils I have used over the years. Better shifts and smoother all round.
im going to say this much about one bike I have. the 72 t500 i run gear oil . the transmissions are notoriously clunky and have 5th gear issues,in that bike I run 75 wt Dino gear oil