Modern Vespa

Hi guys
I haven't posted in the forum for a long time.I just decided to change the gearbox oil on my LML NV from 1991(same as VESPA PX model).I started reading posts in the forums about which oil is best for the gearbox,and I'm totaly confused now.
I used before regular SAE30 oil,but I read now that Piaggio recommends another specs oil.
Here I read that some guys says,that Vespa manual recommends SAE 75W-85 API-4 (I don't know whether that is from a USA market manual),because I downloaded two manuals for Vespa PX and the recommendation in both of them was different specs gearbox oil:
SAE 80W-90 API-4. (I bought yesterday that kind of oil ,brand Mannol.
https://www.mannol.de/products/gear-oils1/mannol-universal-80w-90-gl-4

But now I'm totaly confused,and didn't changed the oil in the gearbox.I'm waiting for your answers so that I can be sure which gearbox oil is the best,before I put it.
Is it SAE30......or SAE75W-85 API-4......or the one I bought SAE80W-90 API-4?????

Thank you in advance
Juno106

Here are the pages from the Vespa Px manuals, with recommended gearbox oil.
Or maybe they are for the newer models of Vespa PX.I don't know.

There's a wiki entry for that!

Gear Oil for Shifty Vespas

I use modern synthetic API GL-4, I like the idea of using gear oil in my gear box.

simple answer to ur q
do we use stoneage overprices two stroke oil
or modern one?

exactly.
75w85/90 api4 with original linings
mineral 10w40 with CR linings

Thanks for your reply guys.What is confusing me FREAKMOPED is that on european manuals it is writen SAE 80W-90 API GL-4 ,and all of you says that in your manuals it is SAE 75W-85 API GL-4?????
I guess they are not the same oils.So which one now is the right one?

Those two are so close to the same weight oil, I would put in either one.

But why does Piaggio recommends two different spec oils in their manuals?
In two I downloaded from internet
it is stated SAE 80W/90, and in those that you all say you have, it is SAE 75W-85?They are probably similar or close,but not the same.One is mineral oil,the second is synthetic I think.
So which one, is the right manual for Vespa PX.Very confusing.

Personally, never liked the later recommended oil. I had customers that smoked their clutches with it. On cork plates, I always used semi-synthetic 20W50 for motorcycles, since it's designed to lubricate the entire engine, including a wet clutch and gearbox. Now that many of us use the CR plates, I use semi-synthetic 10W40, again for motorcycles. Never had any issues with any of these two. Don't forget Piaggio used a "simple" SAE30 before modern oils came into our lives…

I keep on filling with SAE30. It works and is cheap. Why reinvent the wheel?

ditto

There is no Sae 75W85 here in my country.There is 75w80 and 75w90.
I found:
TOTAL 75W80 and 90
REPSOL 75W80( not full synthetic) and 90
ELF 75W80 and 90 too.
So which one above is best for Vespa PX gearbox or should I go with SAE 80W90?
Is the difference big ,between 75W85 and 75W80(or 90)?

https://knowhow.napaonline.com/understanding-oil-weight-numbers-bottle-mean/

Basically, 75W80 is going to be slightly less viscous and 90 slightly more viscous than 85 at 210 degrees F

*edit* I would think that since you want adequate wet clutch plate penetration 80 (vs 85) is a better option than 90 (vs 85)?

Thank you for your reply xantufrog.
I don't know what I want.I just simply wanted to change the gearboy oil and after I started reading the forums about which oil shoild I put.....I got all confused.So it just became a big problem. Everone is saying differently,so I'm just trying to figure it out which oil is best for my LML NV (Vespa Px model ,made in India in 1991). I'm from Europe,by the way.
So should I go with 75w80 Api GL4 (full synthetic or part synthetic,mineral) ?????? Too much confusion.

I guess I will buy SAE 75W80 GL-4 ,but should it be Full Synthetic,Mineral od SemiSynthetic?
Which one doesn't produce corrosion?
And I guess, the oils I just mentioned before are probably for cars or they are universal and can be used in Vespa gearbox?

As I said these oils are ment for cars.Can I use them in Vespa gearbox or should I search oils for motorcycles only? (I don't think I can't find those here)
And they are not 100% synthetic.Is that a problem or not?

I don't believe it matters. Just stick with avoiding the "don't s" from Aviator's wiki entry (detergent, GL5) and roll.

OK then xantufrog.
I think I will go with either TOTAL or ELF SAE 75W80 GL-4.
I really can't bother with this anymore.I hope that I won't have any problem with these oils.
I hope that these don't have any detergents in them,cause they are GL-4 ,or that rating doesn't matter?

Yes, GL4 is the important signifier. I think you'll be fine - you're worrying about oils which are better formulated than the old SAE 30 non-detergent many of us just dump in and ride with. It's a dinosaur that you are treating with modern love

Still something bothers me xantufrog.
Why on the manuals I downloaded(maybe it is European models) it says: recommended gearbox oil should be SAE80W90 GL-4 and not 75W80 GL-4?
Which one is better for older Vespa PX/LML?
Maybe it is better to go with the specs that Piaggio manual recommends for Vespa Px150?
What is your thought on that?

I would go with what your manual says in this case - but bear in mind the information from my link above: you're actually talking pretty small differences here. But I always follow the manual if it offers me guidance

You can see at the pics on my first post here.I downloaded 3 manuals for Vespa PX,and in all of them AGIP SAE 80W90 GL-4 is recommended oil.
I don't know why all of you say that 75W85 GL-4 is recommended by your manual.Maybe it is older manual or maybe USA version...I have no idea.

So it comes down to 2 gearbox oil specs for Vespa PX 150 1991?
Here I can find both of these oils,so which one is better according to you?

Should I buy:

SAE 80W90 GL4
or
SAE 75W80 GL4 ?

Redline GL4

There is no Redline oil where I live.I'm in Europe.
Which specs are better of the two, I mentioned in previous post?

Why not buy the one your manual recommends?

I have no manual.I just downloaded some from internet for Vespa PX 150 or 125cc.In all of them the recommended oil is SAE 80W90 GL-4 (as you can see in the above pics).But all of you here are saying that Your manuals recommends 75W85 or 75W80.I haven't seen that manual yet. That is why it is confusing me.
But it doesn't matter,I'm just asking you if you know,which specs are better: 80W90 or 75W80?

I don't know - I don't think it matters, honestly. You are talking relatively minor weight differences for the otherwise same spec oil. Not for a low powered dinosaur like these (unless kitted out). Again, most of us still just throw old crappy SAE30 non-detergent in and it is perfectly fine.

Maybe the discrepancy is just based on what was commonly available to euro vs us markets. This other wiki implies it's just more changes over time: http://vespalabs.internetscooter.com/wiki/vespa-101/fuel-and-oil/gearbox-oil

So which one is better according to you, for the Vespa PX gearbox?
Help me choose one of these oils,because I can't bother with this anymore.They are all GL-4, I think.

Personally I wouldn't get the Elf oil. Renault had issues with the gearboxes in their F1 cars in the 1980s and they were sponsored by Elf.

If it were me though, as others have said, just go with bog standard SAE30.

They told me that SAE30 oils sold in my country,are not good quality.So I will have to choose one, from the above mentioned.

My comment about the Elf oil was tongue in cheek, they are all far better oils than you need so maybe just go for the cheapest.

honestly, you're overthinking this. Like I said above and Matchless just did: these are ALL way better than the SAE30 motor oil most of us just use.

Literally just choose one. It is going to neither make or break anything.

I just decided to buy Mannol Sae 80w90 gl-4,but just read on some forum that some guy asked Mannol if this oil is apropriate for non-ferous metals,and they told him that it is NOT.I thought that all GL-4 oils are good for non-ferous metals,or am I wrong?
Here is the screenshot of that guy's coment.

All the GL-4 oils will lubricate things just fine, the issue I have with the ones intended for cars is that cars don't have a wet clutch. if it says hypoid stay away from it, your clutch will slip and it will jump out of gear as there is not enough friction on the face of the cross.

I ran Redline MTL (it's non-hypoid) for ~ 20 years in mostly stock bikes and it was fine, but had issues with the clutch slipping in tuned bikes (smallframe)

Now I only run motul transoil. it's still GL-4 rated, but with attention to the function of the wet clutch.
https://www.motul.com/us/en-US/products/transoil-10w30
https://www.motul.com/us/en-US/products/transoil-expert-10w40

This one is not hypoid oil.The other one is.But I have no idea whether all of these oils are intended for wet clutch.There is no information about that in the specs.