Modern Vespa

jerry, hello. You seem to have misunderstood the situation with coolants. You can mix brands if you are very careful and understand the coolant types and standards, but you cannot actually mix different types of coolant. And of course, as you know, some coolants cannot be used in some engines due to problems it causes with radiators and water pumps/cylinder head gaskets etc. You can check this yourself by contacting coolant manufacturers and/or reading up on it on some of the technical sites covering engine coolants.
Just a couple of casual reads, but take a look at the science too. Do your own search.
https://tap.fremontmotors.com/mix-different-types-coolant/
https://mechanicbase.com/coolant/mix-different-anti-freeze/

With respect I think you need to follow your own advice Motovista. I know how it works and you should really read the manual for the Vespa GTS which states how to top off the coolant tank. Grouper has! My owners book tells me to fill between the lower and max lines but not above the max line, with the motor cool or cold. If the expansion tank is filled to the max line, it rarely rises at all above the max line with engine hot. This is due to the very small volume of coolant in the engine. Heat 2 ltrs of engine coolant and it hardly expands at all as you will see if you check your expansion tank when cold, and then again when hot (Do not of course open the expansion tank cap with the engine hot). Another reason for that is the expansion of the cast iron cylinder jacket which negates the coolant level expansion from rising further. In a car this can be different due to differing construction of engines and materials used, but also the greater volume of coolant. More coolant means more expansion.

Even if the coolant expands above the max line in our Vespas because someone is over enthusiastic with the top off, it won't harm anything. At worst it will find it's own level as it's designed to do.

Edit: just FYI, my car tells me to fill the coolant expansion tank to the maximum level when the engine is cold. This is how it works over here, I guess the other side of the Atlantic the forces of nature are different!...

stormrider, I think you misunderstand. all coolants mix readily cause they are all designed to mix with water. this includes even ethylene glycol based and polypropylene based. the only difference is the chemical additives that are touted as extending the life. to say you cant add additives that extend the life of a coolant that didnt have the additive originally is ..in the end what really causes early failure is when its left in too long and screaming to be changed due to how bad it looks in the expansion tank.

I asked you previously to provide simple proof to mix on purpose in a glass jar and see the ugly you tout. you failed to do so as you will this time as well. all the scary pictures on the net are useless once the fact revealed those coolants were used well beyond the "screaming to be changed window"

and you cant refute manufactures who dont like to be sued. picture worth a thousand words. I have been wrenching for 50 years. you are barking at the wrong person AND causing the uneducated to spend money and time when they didnt need to. so bravo to you.

Jerry, you are funny! But thanks for the entertainment. Lol.

Stromrider, coolants in the USA that state on the label that they can mix with any other coolant are AOK. Believe me, if there was the slightest chance of one of them causing damage to someone's engine, they'd have their butts sued off - probably in a class action that would put them out of business.

its the nature of any big business that creates this debate. selling coolant is no small business. the manufacture makes more money by selling the same dang thing with different labels. the dealer charges quadruple for the product. economics for them as well. super easy to say a certain coolant is vehicle specific and its best to buy from us. and it cant be proven otherwise because they aret required to tell you whats actually in the coolant. some just cant see through it. at least his heart is in the right place.

all hard parts in an engine are corrosive in water. always have been. what gets better and better is the number crunchers of manufactures who maximize profit at the consumer expense.

the reason coolant goes bad is no matter how good an engine is built small amounts of that 1600psi combustion go into your water jackets. head gaskets will never seal 100%. but they are getting better and better. it is that "better seal" that is allowing longer intervals before needing to change coolant.. antifreeze itself has not changed over the years.

Hi jim, yes it's the same the world over. But we are really not talking about mixing brands here which is where jerry is getting confused. We are talking about mixing "coolant types". It's this Grouper was concerned about and rightly so too. Mixing coolant types is something you cannot do without usually incurring nasty consequences over time. Hence Scooterwests warning not to mix Coolanol with Groupers factory OAT. The OAT has to be flushed out first. Anyone doubting this should look online for more information or contact their vehicle manufacturer. There's plenty of proper advice and information about this. Most techs already know this sort of stuff as we are trained to know about it so we don't damage customers engines.

But more widely it should be understood that different coolant 'types' use different methods to protect your engine from corrosion. Some lay down a "carpet" of protection on all internal cooling components to stop corrosion (IOAT does this and is still common in the States), and some just attack corrosion at source when the coolant comes into contact with it (eg: OAT). The two types of coolant must never come into contact with each other or a chemical reaction takes place that can render an engine useless over time. Mixing them in a glass does not produce the same result as in an engine either.

So if someone decides to replace their engine coolant you must know what "type" (not brand necessarily) of coolant has already been in the engine. That way you know what is safe to put back in or even to top off with. If it's been an IOAT it's very hard indeed to flush out the remnants of that coolant because the blanket of protective layer it has put inside the engine will not come out easily and it even sticks to the inside of hoses. In the workshop we have even had to replace the coolant hoses to get rid of the IOAT completely. We would never recommend replacing IOAT with an OAT coolant as it's an expensive procedure and we have done it when a customer has requested it only. It has to be done if refilling with a different "type" of coolant to be safe when you are working on a customers vehicle that may have cost them huge sums of money. If you don't do that the customer will get a nasty surprise and big bill in the future.

So best advice is not to mix coolant types (remember that's different to coolant brands) that are incompatible. There are dozens of differing types of coolant, each with a slightly different way of working. None of them completely mix properly with each other but they do mix just well enough to work, but usually less efficiently than that of a pure coolant of one type. Others, if mixed will cause considerable problems for the owner if mixed. That's why owners need to be extremely careful. Coolants are THE most misunderstood components of internal combustion engines.

In order not to be mistaken, I "always" keep in my garage a liter of each liquid I need to top up, engine oil and coolant.
Not brake fluid which (I insist) should not be topped up but only completely replaced at the intervals recommended by the manufacturer and I have it done in an authorized workshop.
I hardly add water to the cooling circuit, at most I prepare a one liter container (sorry for the metric system) and mix distilled water (20%) and coolant and shake them to mix them well; I would add that if you have the complete change done at fixed intervals (or you do it yourself) there is no need to add water.
Also check whether the container of ready-to-use coolant indicates whether it is already diluted or concentrated to be diluted.
I like to read the technical advice on the forum but I always weigh the meaning ...
My advantage is my experience with two and four-wheeled vehicles gained over forty years of basic use and maintenance but also attending proven workshops where I can ask for advice.

I love my air cooled 150.

Just sayin.

...but how much I envy you for this you cannot understand ...

Dang! Tell us how you really feel man!

Agreed, air-cooled ways is best ways

Who's Stormrider? :?

Jim Morrison?

Leone Di Lernia.

I want to think everyone who has contributed to this enlightening, if somewhat contentious, thread.
I come from the completely inept school of vehicle maintenance; if there is a way to screw things up, I will figure out a way to do it.
Last year, when my 2009 250 GTS had to be brought to the closest dealer 150 miles from home for a fuel pump recall and valve adjustment, the service guy told me it looked like my scooter had been (abused/ignored/ridden hard) for its eleven years and almost 20K. I was a bit insulted, but soon realized that I had no right to be. He charged me just over $300 including belt, valve adjustment, and repair of wiring that was burned. (I guess that’s why I occasionally smelled a whiff of burning electrical stuff over the years; never really looked very hard to find where it came from and it always went away quickly without any damage, and I hadn’t smelled anything in a couple of years).
As I was leaving, he told me to just ride it until it dies and don’t worry. I’ve ridden it about 2K since with zero problems.
I do change the oil and filter every two years (even though I manage to spill it on the center stand) but even though I bought a couple of air filters for the two bikes, I never changed them because it looked too complicated.
Many years ago (perhaps seven or eight) I brought both bikes to a Brooklyn shop and paid for new tires, belts, rollers, and coolant flush. That is the last time I as much as checked my coolant. The bikes have never come close to overheating and the fans always work perfectly.
Reading this thread motivated me to put down the iPad and check both GTS bikes. Both had yellow coolant, and each was slightly below the minimum. Looking in my garage cabinet (my wife made me buy it recently so that stuff wasn’t all over the edges of the floor) I spotted one bottle of coolant which said on the label that it was good for all American, Asian, and European vehicles, and it was yellow.
I took a shot and added perhaps a couple of ounces to each so that each was beyond the minimum. I’m hoping for the best.
Now, all I need is a thread about brake fluid, as I’m pretty sure the stuff in one bike is 15 years old and the other 12. Pads are original on both and the brakes work well on both as far as I can tell.
Oh, one more thing, and I hope my good friend jimc will forgive me; I’ve never disconnected all that evaporative gas tank junk, I often fill the tank right to the top, and I’ve never had an issue. Perhaps I just live right.

No worries - the Evap Crap can be left unmolested if there aren't any problems. However, when the bike doesn't run right, it's the first thing I'd disconnect.