Discussion of Rights and Wrongs about Fluid Exchange for CVT, AT, etc. – Car Consultation Counter Part.6

This consultation is about the fluid replacement of the automatic transmission that I myself am quite troubled.

I am always indebted to you for the consultation of maintenance work and the car in general.

The matter that I would like to consult with this Consultation Counter this time is about the pros and cons of the fluid exchange of CVT, AT, etc. transmissions.

Recently, when I went to the dealer in the recall of Prius alpha that I owned, I was suddenly worried, "Is it necessary to change the CVT fluid of Prius alpha?"I asked.

The dealer's response was, "Replacement of prius alpha CVT fluid is basically unnecessary.The case that the trouble came out to the transmission without fluid replacement so that there is no description that it is possible to exchange it every tens of thousands of km in the owner's manual is not experienced by us and it is judged that it is all right without replacement.However, if the owner himself wishes to exchange by all means, after explaining that there is not a little risk of problem occurrence in the original and there is no guarantee, we will do the replacement work if you are satisfied, but do not recommend the exchange from the dealer side.It was a thing.

Prius alpha is a special car called a hybrid car transmission will be considerably different from the mechanism of the conventional car and the degree of consumption of the internal parts will be small, but I can be convinced that the fluid no replacement, For transmissions such as CVTs and staged AT installed in existing gasoline and diesel vehicles, the idea does not coincide with the case where the replacement is recommended by the automobile manufacturer at tens of thousands of km, or there is a case where the replacement is specified until it breaks down.

On the web, there is an opinion that the fluid of the transmission (including hybrid vehicles such as Prius) should be replaced regularly every tens of thousands of km because it deteriorates with consumables, The current transmission is divided from the head, and there is an opinion that it is good to remain unreplaced considering the risk of the trouble occurrence by the exchange that it does not break easily, and which is really right?And lack of knowledge about cars is up to me so questionable.

I would like to share my views on the pros and cons of the fluid exchange of transmissions from the perspective of Takeshi, a professional mechanic.

First of all, i would like to talk about the CVTof of a hybrid car such as the Prius that the questioner asked at Toyota sales company.

Because the notation such as the catalog has become "electric CVT", I was embarrassed, and I also mistaken it as a special electronic control version of the belt type CVT which sandwiched the steel belt with two pairs of pulleyats at first.

Unlike other transmissions, the machine structure of the transmissions installed in the THS (Toyota Hybrid System) is extremely simple.

A generator, engine, and motor (output shaft) are connected to the planetary gear unit (planetary gear mechanism) with three connections (Sungear, Planetari Carrier, Outer Gear).The engine is used for power generation and driving, charging excess energy, and precisely controlling the input and output to achieve continuously variable speed.

While the control is complex, it is a simple combination of a simple spur gear with only planetary gear and final gear mechanically.I'm sure it's okay to replace the lubricated fluid, and I don't think there's any big risk in replacing it.If you don't feel comfortable with the old fluid in it, you can replace it.

On the other hand, the belt type CVT, which is sandwiched between two pairs of pulleys, uses friction between the metal between the belt and the pulley to transmit power.

While high frictional force is required, the belt must slide on the pulley at the time of shifting.In addition, it is a mechanism full of technical issues that require suing both conflicting properties, such as not causing seizure while obtaining high frictional force.

Because friction between metals is actively used, power transmission efficiency is not high compared to other transmissions.However, sticking to the CVT of the steel belt type, the main reason that each manufacturer tackles the challenge for a long period of time is that the real fuel consumption is improved by continuously variable without interruption of wide range of shifts.When a good driver controls a manual mission, it is the same logic that the fuel economy is very good.

The fluid used in the CVT of the steel belt type is prepared as standard several kinds according to each company and various transmissions.It is easy to imagine that the CVT fluid has a large part of the mechanism that consists of an exquisite balance, and a special formulation will be used.

If the management of oil volume and oil species is not properly managed, the risk of failure increases, so while there is an idea of using it until it fails without replacement, as long as you properly select and manage the oil species, I think that it is also that a good drive feel is obtained for a long period of time more durable than the exchange.

This can also be said for conventional stage DANs.Even if it is not as severe as the belt TYPE CVT, since it is a transmission with friction elements such as wet clutches and band brakes, fluid replacement is necessary in order to slow the wear of the friction element for a long period of time, but oil type, oil amount, The risk of failure increases if the replacement is not properly used.

Do you have a good understanding of each mechanism and will replace (or do not replace) the standard fluid at the appropriate time in the proper manner?

In my case, I will always consult with the owner about the fluid replacement of the automatic transmission.

We look forward to hearing your questions and consultations.We will answer simple questions that you can't hear anywhere for free.

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