Fully synthetic worth it?

[Andy J]

I'm going to be doing a trans oil and filter change on my 96 C4. I'm just musing as to whether to go to the expense of using a fully synthetic fluid. Had a look on the Opie oil website and I can get a "normal " ATF to the correct spec for about £40. Or I can get Motul fully synthetic again to GM spec for £10 a litre so a fair bit more.I'm happy to spend the money, after all it wont be done again for a while but is it overkill?

 

[teamzr1]

GM recommended Mobil I synthetic for the C4s
Mobil I has synthetic for engine, tranny and rearend which I used with my C4s including when racing
Has better properties and handles heat better.

 

[Andy J]

I knew they recommended synthetic for the engine but not the transmission. That solves that then! Thank you.

 

[teamzr1]

Here is the synthetic ATF if using Mobil I
Should be able to get it also for the UK Amazon or other places

Mobil I ATF Synthetic

If replacing fluid for rear end, also synthetic, I have been using this even in my C5 rear diff for many years
Cab choose different weight wanted

Rear diff

 

[Andy J]

Thank you. Really appreciate it.

 

[teamzr1]

I just added to post if wanting also for rear end

 

[Andy J]

Thanks. Just to be sure, how much do i need for the transmission? Im thinking 6 Litres which i guess is a similar amount to 6 Quarts?
Either way, i want to get enough to do the job in one go rather than need just one more bottle!

 

[teamzr1]

Hi Andy
I assume you are only going to drain the pan then 5 quarts or a little more
If need be, your owner's manual would tell you

I suggest IF taking A4 pan off, then also replace the filter

 

[Andy J]

Yes i have the filter and a new gasket sitting here waiting. So 6 quarts/litres to be sure.
Always better to be half a bottle over rather than needing half a bottle at the end!