damper oil

[wole]

hi all everybody seems to recommend sae 40 oil in the dampers how about mixing some ep 80 with some 20/50 ? if so what ratio thanks wole.

[mike.perry]

One of your favourite subjects Roy, over to you.

[jaguar68]

You can use motorcycle fork oil. It comes in the correct weight.

Regards

John

[bmcecosse]

I suspect motorbike 'fork oil' is only SAE 10 or 20...... Mix up any combo of oil you like - I have used EP90 in the past in my Rally Minor - but I would prefer not to get the blame if it goes wrong for anyone using that stuff - although it was fine for me! SAE 30 is available in Tesco for lawnmowers - and SAE 40 is available at motorbike places for the engine. That's about as far as I am prepared to recommend...........

[Stig]

I thought I'd read this somewhere. EP90 isn't as viscous as you'd think from the number. Maybe not an authoritative reference but according to Wikipedia:

API viscosity ratings for gear oils are not directly comparable with those for motor oil, and they are thinner than the figures suggest. For example, many modern gearboxes use a 75W90 gear oil, which is actually of equivalent viscosity to a 10W40 motor oil

http://en.wikipedia.org/wiki/Gear_oil

I'm assuming that applies to EP oils, I'm not familiar with the GL ratings they list.

[bmcecosse]

Yes - that may be so. It's not clear what viscosity the EP oils are. Just use SAE40 - you won't be disappointed.

[IslipMinor]

There is a pretty good equivalence in viscosity between 'gear' oils (EP and straight) and 'engine' oils.

80W gear oil = 30 engine oil

90 gear oil = 40/50 engine oil

140 gear oil = 60 engine oil

The multigrade oils work about the same way as well.

As suggested, for dampers a straight grade engine oil is the best choice, as there is a limited temperature change range, so no advantage in using a multigrade oil.