[blue2000s]

Originally Posted by JFP in PA

First, we regularly do coolant changes at our shop, so we get to see the good, the bad and the ugly. The Porsche coolant is actually some pretty good stuff; coolant drained out after 8 & 9 years still tested well for freeze point and pH buffering, so it was holding up without issues.

From time to time, we get cars in that are overheating, and when we open up the system we find a mix of gel and coolant, almost always just after the system had an issue (like a coolant loss on the road due to a slightly cracked surge tank) needed to be “topped up” with another coolant product. The most often sited product (we have never been able to positively identify it) was that someone had added a “Dex Cool – type” coolant to bring the system up to fill levels. Shortly there after, problems begin, usually in the form of running hot. At this juncture, the car goes on straight “time & materials” charge basis to flush out the crud with lots of hot water; which is time consuming as Hell. You simply have to keep running hot water thru the block and radiators until the stream runs clear.

Based upon our tests with the OEM coolant showing it holds up well, and which in reality is only a few bucks more than the after market stuff, we stay with the factory coolant and tell our clients not to let anyone add anything else to it in a pinch. If you have a leakage/low coolant warning light, add distilled water to get the car home or to our shop so we can fix it properly. This is also what most dealers tell their customers when they call in with this issue.

Could you use something other than the OEM stuff? Sure, once the system is cleaned out, I’m sure there are several aftermarket products that could do the job. But because the OEM stuff is readily available, is not all that expensive (about $20 a gallon compared to the $12-14 a gallon aftermarket products), has demonstrated the ability to hold up well for a long time in cars that run rather hot (while your dash gauge may read 180, I’ll bet money a PID capable scanner plugged into your OBD II port will read 210-215 F on a 72 degree day); why bother with an unknown coolant?

As for my comment on Mobil 1; we stopped using Mobil 1 products several years ago. I have never subscribed to the “0W-anything” oil theory, and Mobil 1 has become infamous for reformulating their products with no notice, and have actually lost the ACEA A3, B3, B4 ratings for several of their oils (such as the 15W-50 grade, which used to have great UOA performance before, but now has a lot of trouble “staying in grade” after short usage in a low performance street car). So, we do not use any Mobil 1 oils, and do not use anything lighter than a 10W-40 in a M96 engine car. Our UOA continue to look great, and we have had absolutely no oil related issues.

Hope that clears it up for you………

Thanks for clarifying. Your input is appreciated. It sounds like you don't have any experience with what is compatible with what, just that you've seen what happens when an incompatible coolant is added.

I understand that your point is better safe than sorry, and I can appreciate that. Especially from the standpoint of someone who's got to get it right the first time or the car's coming back with expensive problems. But from a smart consumer standpoint, it makes sense to find the identical product for half the price.

Here's a little experiment I'd like to see. Take some of the Porsche coolant and some of the other coolants, like dex-cool, G05, that prestone universal stuff, mix it, heat it, leave it for a week and see what happens. Has anyone ever tried it?