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Protecting the M96 - thermostat and radiator

JagdHamster

JagdHamster

New member
Hi Guys,
I have read that many recommend a Low-Temp Thermostat for the coolant system in order to minimise the risk of bore-scoring, etc. on M96/M97-eninge cars.

Apparently some also recommend an extra radiator as well.

Have any of you done this, or know of information about it? If it's not too tricky, I'm interested in doing this.

Also, I'm going to put Millers Nanodrive oil (now called CFS) into her. Should I go for thicker 10W-50 oil in (75K miles), or stick to 0W-40?

Cheers,
 
I had fitted, earlier this year, a low temp thermostat and a new water pump at the same time whilst it was being done. It certainly runs cooler gained about 0.5 bar oil pressure but the downside is I have lost 3 MPG! On the oil I run mine on 5W-40.[:)]
 
Now the mileage is up at 80k i use Millers CFS 10W-50, bit of ZDDP and a touch thicker so it should help.
 
Once the thermostat is open overall cooling not a problem. Its localised overheating that scores the bores. Third radiator only really needed by tiptronic equipped cars, which is why they are fitted as standard for those.
 
Thanks, Geoff (and everyone, again).

I'll be ordering Millers CFS and that thermostat very soon (just need to check if there isn't one on the old girl already, as she's been well looked after).
 
I was adviced by a well known independent to not fit any low temperature thermostat these engines if running at the correct temp are meant to run hot, it's better for the engine, he stronly advised not to mess with this. I took his advice as they have been brilliant in the past and they are a very well known specialist.

Just what I was advised.

Cheers Phil
 
It shouldn't make much, if any, difference to the running temperature. The lower temperature thermostats just open at a lower temperature, allowing the water to circulate earlier. Warm-up time will be increased, but once the water is up to operating temperature it wouldn't make any difference if it was a 71° or 81° thermostat - both will be wide open, and the cooling fans will control the water temperature.

The theory is that the water jackets of the 3.6 engine are narrow around the cylinder bores, and if higher loads are applied to the engine while the thermostat is closed it can cause localised boiling, reducing the cooling of the cylinder walls, and causing bore scoring. IMO the low temperature thermostat is a good idea, but there is no substitute for being careful during warm-up. The lower fuel consumption will be due to the extended warm-up time, when the engine will be running richer.
 
I have now read all of Hartech's stuff (many, many interesting pages) and wished I'd just read Richard's excellent post above instead :)

Great summary.
 
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