D5 (2005 on) D5 Manual Gearbox Additive?

[iantowil]

Thought it probably best asking this question here - I have a manual gearbox on my C70 D5 that I assume is pretty heavy duty so tends to be quite clunky on cold mornings and maybe not the slickest unless the weather is hot. Does anyone know of or experience of a good gearbox additive. I've used the Molyslip Gearbox paste additive in my 2.5 Cougar 10 years ago and it made a nice little difference, making it a bit smoother. Not sure if this is suitable for the D5 manual box though - anyone have any experiences of this type of thing?

[paulhanson30]

Hi you should not need additives, try using fully synthetic oil in gear box that should help

[jamesferns]

Originally Posted by iantowil

Thought it probably best asking this question here - I have a manual gearbox on my C70 D5 that I assume is pretty heavy duty so tends to be quite clunky on cold mornings and maybe not the slickest unless the weather is hot. Does anyone know of or experience of a good gearbox additive. I've used the Molyslip Gearbox paste additive in my 2.5 Cougar 10 years ago and it made a nice little difference, making it a bit smoother. Not sure if this is suitable for the D5 manual box though - anyone have any experiences of this type of thing?

Do not add molyslip or any other additive, end of story.

[iantowil]

Sounds like you're not a fan of gearbox additives - bad experience or evidence against their use?

[CJL]

You could try changine the oil if it's old. Did this on an M56 gearbox after 100K miles and it did help a bit. I'd use the genuine Volvo oil too without any additives.

[jamesferns]

Originally Posted by iantowil

Sounds like you're not a fan of gearbox additives - bad experience or evidence against their use?

No im not, when volvo designed the box they specified a lubricant that best served its needs therefore what volvo specifies is what to use, any additives that may be required will be incorporated into that lubricant, Best bet replace the old oil with new, and if you understand the principle of how a syncromesh unit works you will realise a molyidimium based additive is just what they dont need.

[iantowil]

Please enlighten me on why a syncromesh box doesn't like a molybdenum based additive. Keen to know the technical reasons.

[RobbieH]

Have a look / search for threads on gearbox problems. Autoboxes in particular are sensitive to the oil used. Get it wrong and you are looking at the thick end of a wedge.

A recent example
http://forums.t5d5.org/topic/18593-s...03#entry212503

TBH I'm not bothered about the technical reasons although I will read and absorb anything that's out there. Nothing else than genuine Volvo fluid will be used in mine (if anything needs changing or adding). There's enough evidence to show the boxes don't like anything else than what they were designed for. End of.....

[Clan]

Originally Posted by iantowil

Thought it probably best asking this question here - I have a manual gearbox on my C70 D5 that I assume is pretty heavy duty so tends to be quite clunky on cold mornings and maybe not the slickest unless the weather is hot. Does anyone know of or experience of a good gearbox additive. I've used the Molyslip Gearbox paste additive in my 2.5 Cougar 10 years ago and it made a nice little difference, making it a bit smoother. Not sure if this is suitable for the D5 manual box though - anyone have any experiences of this type of thing?

The original oil will last and last , in fact there are many 20 year old 850's etc going around fine with original oil in , It is the best quality synthetic .
However the latest oil you get from the dealer is slightly revised to help with cold weather changes on the later cars , it wouldnt do your gearbox any harm and may help it if you are having trouble . BUT your problem may be clutch drag , you really need to get it diagnosed if you have a problem .
Yes the 850 gearbox is extremely strong and has huge thick gear wheels inside to take the power of the T5 engines .
Additives of any type are forbidden by volvo . They make the gearbox and choose the oil as to not need anything else .

[iantowil]

Thanks for the replies gents. I don't have any big issues, just abit clunky on a cold morning, but nice and smooth on a summer afternoon so thought about a possible additive as I've had an improvements on a few cars in the past - 2.8 Capri, 2.5 Cougar, 1.1 Fiesta ;-)

I'm no big gearbox expert, so thought I'd ask. If I had an automatic I wouldn't think about adding a thing - the term "sludge pump" comes to mind so don't mess with the sludge as its pretty important - or at least that's my simple logic. I think a manual box should be less finnicky though - that said I'm also very cautious and after the answers here will probably not do anything. Interesting you mention the modification Clan - and its reason is to ease the very thing I notice when cold.

On the point of using only Volvo recommended lubricants - I understand that Volvo will have done some testing if not alot of testing but mistakes have been made in the past. Engine oils have broken down under high shear and failures have resulted. I did love the post on DPFs where "the doc" asked the Castrol technical support could he use diesel to top up his engine oil and the tech guy laughed at him - don't hink he laughed when he new the full story on DPFs. Can you imagine Volvos reaction to your warranty if you said you tipped a litre of diesel in your engine oil? I guess the point is they're good, but not infallable. However, thanks for your replies, points taken on board - no molyslip anytime soon ;-)