Manual transmission roughness

A Toyota Avensis 1.8 GS, manual gearbox. It has done 113,000 miles. A slight vibration has occurred in the gearbox. It is usually when
decelerating and is reduced when dropping to a lower gear. It is not there when accelerating. When depressing the clutch and keeping engine at the same revs it go away, which indicates it is not the driveshaft. Does anyone know what it is? Clutch?
On another point the likes of Slick 50 say there products prevent noises in old gearboxes and rduce wear. Are these additives and good? Do they work?
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On 12/1/10 5:16 PM, Scribe wrote:

They make lots of money for the people who sell them. They don't help the people who use them, however.
They are a waste of money.
Jeff
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I supposefully synthetic gear oils are the ultimate then. Not snake oil.
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On 12/1/10 6:13 PM, Scribe wrote:

Of course, synthetic gear oil will not reverse damage.
Jeff
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I assume it will reduce the wear rate.
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"Slight," makes me wonder why you even consider it worth worrying about. After 113,000 miles, it could be anything, and is probably nothing to worry about. Why don't you drain and refill the transmission fluid? I'd just use regular fluid and avoid the temptation for synthetics or for the Snake Oils.
And, your car doesn't have a driveshaft, per se. It has drive axles (one to each front tire) that you have not successfully eliminated from the picture. Each half-shaft has an inner and an outer CV Joint, giving you 4 CV joints. Any one of them can give a vibration when they are loaded either in the direction needed to propel the car forward, or in the direction they are loaded when the car is slowing down. By downshifting, you are changing the load and the harmonics at which the vibration occurs. If you turn the steering to full lock and drive in a circle, then turn full lock and go the opposite way, and hear any clicking or feel any vibration then you probably have a CV joint on the way out. You can clean and re-lube the CV joints, but most people just replace them.
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The idea is to identify what it is and do something, if at all, to nip it in the bud. I can live with it. Most driving has been on motorways, so gear changes are the equivalent of a car that has done half, or less, the 113,000 miles.

Fully synthetic is not snake oil. Mobil 1 make a transmission oil, this is supposed to not be influenced by temperature highs and lows that much. Yesterday in -2C the gears were hard to change until the car had warmed up. Fully synthetics are supposed work better at lower temperatures (not thick like syrup).

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Full synthetic is not snake oil, and I didn't mean to suggest that it was. It is expensive though, and I don't think you will benefit from the added cost. I'm not sure, but I think your car takes automatic transmission fluid even though you have a manual transmission.
My point was that your best nip-it-in-the-bud approach right now is to replace the fluid.
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The oil is normal gear oil. I forget the viscosity.

I intend to do that. I noticed this on wiki for what it is worth. I do not like wiki that much as some of the info is way out and at times childish and childishly written.
"Fully synthetic gear oils are also used in many vehicles, and have a greater resistance to shear breakdown than mineral oils. They can improve the shifting performance of "difficult" gearboxes, where the excessive slipperiness of some mineral oils can impede synchromesh action." It does request a citation. http://en.wikipedia.org/wiki/Gear_oil
So, it would be a good bet to change to a fully synthetic oil for better shifting, according to wiki.
Back to snake oils. This Slick 50 has been around for about 25 years and still sells well all over the world. Many people swear by it. I thought maybe there must be something there. I know they were taken to court for exaggerated claims.
About after market additives. Fuel additives do work. I put a small bottle of Red X into my tank before each annual inspection. It always passes. Also the idling becomes smoother. A friend who does annual inspections say they recommend people to put Wurth, Red X, etc, in as they do improve emissions and get a car through the test. They will put Wurth to failed cars and tell the owner to drive around for a day and come back in two days time. It always works.
Stage coach tested an after market additive in half their vehicles and checked them against the other half . There was great improvement. They put the additive in all their vehicles now: http://www.stagecoachgroup.com/scg/media/press/pr2010/2010-01-26 /
This begs the question. Why isn't it in all fuel? And this also trashed the well known responses, "if it was good enough the car makers would do it?" "if it was good enough the oil companies would put it in the fuel?" "if it was good enough the car makers would recommend it?"
A old neighbour of mine is a an auto design engineer. I recall he said in older engines "moly" based additives do make a difference "and " reduce fuel consumption a little.
It appears that some say they work and others say "snake oil".
I was wondering if anyone had used an after market gearbox product and what the "honest" results were. If one had decent feedback then it might be worth a try. Otherwise I an using a fully synthetic gear oil. These oils also last far longer than mineral oils.
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On 12/4/10 4:00 AM, Scribe wrote:

I wouldn't take advice from a source that anyone (even I) can edit for a device that costs $1000s of dollar to fix or replace without checking the references and doing a search of my own.

Many people swear by distilled water as a cure even there is no evidence at all that it works and the conjecture on which it is claimed to work makes no scientific sense at all. (<http://www.quackwatch.com/01QuackeryRelatedTopics/homeo.html )

Yeah, right.

Read the real info about ENVIROX, the aftermarket product they are using. It is specifically designed for diesel engiens and has a catalyst in it. That is different than using any old fuel additive (Wurth, Red X, Bullshit, Made up claims, etc.).
http://www.oxonica.com/energy/energy_envirox_intro.php

How would you know without knowing what's in the particular product and without a real test of the product? Not just some backyard mechanic who "swears by it."
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Yeah, right. On borderline fails they have not had one not pass on re-test using Wurth. Yeah, right.

The point is that additives DO WORK. Not all are snake oil. ENVIROXT madea differnce in real world testing of a fleet. So why isn't it in all diesel fuel? The testing friend of mine swears by Wurth. He told me to put it in my car (the fuel injection cleaner). I put in Red X and it passed. I DO notice the idling becomes more steady, and "slight" increase in power on take-off.

If enough feedback say putting this XXX product in the gearbox will smooth out the changing and overall running then I may give it the benefit of the doubt.
I prefer taking notice to those who have used a product and their finding, not a 100% sceptic, who has been proven wrong that additives do not work. Stagecoach proved they do.
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New cars might get synthetic gear oil (transmission oil and/or differential oil) but I doubt your Avenis can be counted among these models. I would not bother with synthetic oil in a transmission that's already 115,000 miles old, and ten years. Your car is a very low performance vehicle -- it is an econobox not a sports car.
I see no benefit to synthetic oil for you.
If you had a Turbo Supra or some other performance machine such as that, then by all means dump the dino oil and put in a load of synthetic.
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It was an option on the first service by the dealer. Mobil 1 transmission oil. The recommended engine oil is semi-synthetic.

It does 115mph. I fail to see that marketing segment (sports) matters.

The engine has had fully synthetic from the first service. The gearbox was mixed, as to what the dealer had. Sometimes fully synthetic gear oil. The extra cost is not great at all.
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I'm confused.
You are sold on synthetic AND your mechanic wants to give you the upgrade to synthetic at no cost or a minimal cost. Do it.
I don't see the advantage, but if I could get synthetic transmission fluid for free as compared to dino oil for the same job, I'd do it. There is nothing wrong with synthetic oils anywhere, the question is, is the extra cost worth the small added benefit? YOU think the answer to the questin is , yes. So go for it.
I don't think you're having anything wrong with the transmission that I can help you with except to say, change the fluid. I would not use synthetic because I perceive that it costs more and there is no benefit.
I saw that Ray suggests you can be noticing the affects of worn transmission and/or motor mounts. That's certainly a possibility, and one that is frankly pretty high on the list. If this is the problem, there is no fluid that will fix it.
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I am not sure of the full benefits of fully synthetic oils over mineral oils in gearboxes. They do last longer and are difficult to break down, so I would say the befits are greater than what most think. I know of cab drivers who do high mileages, and can't always get a service on time maybe overrunning the service interval by many 1000s of miles, use fully synthetic oils in engine and g/box as an assurance against service overruns.
About 15-20 years ago I did some work in an oil research lab. The Tribologists said "only ever use fully synthetic oils", as the lubrication is vastly superior in every way. Most people thought it was only for "sports" cars, they said use it in all engines. One would take a sample of oil from his car and test it before any changing of oil. He went 60,000 miles on Mobil 1 changing the filter every 6,000 and topping up a little, and it still did not need changing. I have used it ever since. One also said it is best to use from new the likes of Mobil 1, newer products are on the market now, and use an oil filter with finer filtration. He said the engine will then just last and last. I have not taken up the filter advice, Maybe I should have, but their views have proven correct with me. 113,000 miles and not once topping up the oil level.
My car from new came from the factory with semi-synthetic, the over to Mobil 1 at 500 miles. It has not faltered or used one drop of oil. The engine still sounds and feels like new when cruising. The superior lubrication qualities of synthetics are pretty well known. There is only one choice. Once an engine is worn, and oil consumption starts, then semi-synthetic oil like Castrol Magnatec was recommended.
The gear fluid does need changing and I am 99% set on a fully synthetic despite the extra cost - which is not great. Because the gearbox is worn it does not mean I have make it wear any quicker. I was just unsure if there are any after market gear additives that benefit worn g/boxes.
I will check the mounts, maybe when the Spring comes, as it is below freezing most of the time here now.
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First, make sure that you have the correct transmission fluid - most newer Toyotas use ATF in manual gearboxes and using gear oil will cause difficult shifting.
Check your transmission mounts and engine mounts, particularly the ones nearest the firewall as broken or worn mounts can cause the symptom you are describing. I can't think of anything internal in the transmission that would likely cause a vibration only on deceleration.
Stay away from additives as most cause more harm than good. Additives can change the way the synchros bite the cones, causing rough shifting, particularly downshifting.
--

Ray O
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On 12/5/2010 1:14 AM, Ray O wrote:

I was thinking of using
Synthetic Manual Transmission and Transaxle Gear Lube 75W-90 API GL-4 (MTG)
http://www.amsoil.com/storefront/mtg.aspx
on my first manual transmission fluid change just due on my 07 Corolla. I called the dealership and they said that synthetic oil is rarely used in manual transmissions. They didn't discourage the idea, but they didn't feel is was really necessary. I wanted to get easier shifting in the cold weather. Any advise?
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That is what I want. Dealership advise? Mmmmmmm. They tend to just quote out of the manuals in my experience.

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On 12/6/2010 6:35 AM, Scribe wrote:

After a lot of hunting, I finally found a transmission shop in town who sells this Amsoil product and keeps it in stock regularly. Paid $15.10 plus taxes per quart. I expect to have it installed in the new year when my ECM recall gets done. I'll try to post the results in a few months time.
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Using gear oil in a manual transmission designed to use ATF will cause harsh shifting so double check your owner's manual to see what type of lubricant is specified for your transmission. ATF is less viscous than gear oil so it is easier to shift when the fluid is cold.
--

Ray O
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