Different Greases

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dazthephot
Joined: Wed 09 Apr, 2008 18:58
Posts: 254

  Z3 roadster 1.9i
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Different Greases

Post by dazthephot »

We pick things up as we go along and we learn all sorts as home mechanics. Is there a definitive guide to grease?

I ask because I’ve learned about silicon being dot 4 friendly and all
Kinds of things like that. Things like hub grease cv joint grease etc are all different so I’d like to know why and what is best for different areas.

Ta


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Mike Fishwick
Joined: Fri 19 Jun, 2009 10:27
Posts: 2051

  Z3 roadster 2.8
Location: Daglan, France

Re: Different Greases

Post by Mike Fishwick »

Do not become confused with silicone brake fluid and silicone grease! They are different compounds with different properties, and it is not wise to mix them. I always lubricate the caliper piston/seal area with brake fuid, which is entirely safe. Contrary to popular wisdom, the grease often provided with new brake pads is to lubricate the contact areas between the pistons and pads, and the areas on which the pads and calipers slide, not the pistons and seals!.

Normal grease is an easier proposition, as basically any high melting point lithium-based grease is satisfactory for hub bearings and drive belt tensioners etc. Suitable greases are Castrol LM or Shell Retinax. Any reasonable silicone grease is fine for periodic lubrication of polyurethane suspension bushes.

CV joints are lubricated with a medium molybdenum grease intended for such an application. There are always equivalents, if you search around. For example, BMW used to reccommend an expensive Molykote MRM2 for the rear wheel drive splines of their motorcycles. The specified grease for the CV joints used on all FIAT/Lancia cars was FIAT BRM2, with an approved equivalent of Molykote MRM2. The FIAT grease came in 850 gramme tins, at a fraction of the price! After 40 years I still have my original tin!
A Z3 is not just for Christmas - it's for life!

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dazthephot
Joined: Wed 09 Apr, 2008 18:58
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Re: Different Greases

Post by dazthephot »

Fantastic answer thank you and a great reference.

I got my new pistons and seals from bigg red and they came with silicon grease for the seals and to aid reassembly. ( I recently had to service the fronts due to seized pistons)

It was the fact that I could use the grease in a chamber that contains brake fluid that was a surprise to me. I suppose that over time the grease will wear out but I was a bit concerned with contamination. My fluid is standard dot 4. (Isn’t dot 5 silicon?)

I’ve always stuck to coppercrest for the back of brake pads and careful not to get it in the pad or disc.


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TripleA
Joined: Sun 26 Jul, 2020 09:49
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  Z3 roadster 1.9

Re: Different Greases

Post by TripleA »

Hi
Many years ago I quizzed a representative for the biggest supplier of fuel, oil and grease as to his best poduct for my use.
He suggested the "finger test Does it feel slippery- its Okay" Yes we have moved on but some parts of the car need little more than slippery

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dazthephot
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Re: Different Greases

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