R35 GT-R Maintenance Logs Part 2 - Coolant and Diffs

In my last Maintenance Log I talked about the two services that people ask about the most when it comes to the care and feeding of an R35 GT-R: oil changes and transmission fluid swaps. This time I brought in my car for two less commonly done but no less important services: changing the engine coolant and swapping the differential fluid.

Now, since you're reading a car blog like this most likely you're a die-hard gearhead who already knows why all the regular maintenance items recommended by the manufacturer are needed and you're not one of the millions of clueless commuters who think their vehicle runs by the magic of irradiated gerbils and unicorn dust and all those service jobs are just a scam by the big, bad car company to take away your hard-earned ducats. However, this being the interwebs and there's always a possibility you may have wandered onto this site without the benefit of already being omniscient like some internet commenters seem to act (heaven forbid that you should ever show weakness by admitting to ignorance and searching for answers to stuff you don't know) then I'll bid you a hearty welcome and explain to you why a periodic coolant swap is a good idea. Maybe it'll help you on the path to gearhead nirvana.

So, why do a coolant swap every few years, or in the R35's case every 2 years or 24,000 miles? Does the coolant go bad from absorbing too much testosterone or losing vitamins or something? Is there an expiry date to coolant like that three year-old Viagra you keep under your bed “just in case”?

Well, coolant does essentially “go bad” after some time in an engine but not from losing vitamins, instead it loses the beneficial properties of the additives that are included in modern coolant solutions and over time it ends up containing too many contaminants. Modern coolant additives help keep your water pump lubricated and happy so like oil keeps your engine spinning nicely, fresh coolant can help ensure your water pump does the same. Additives also help prevent corrosion since most modern coolants are still water based. Replacing the coolant periodically not only refreshes that rust protection but also removes contamination in the old fluid from whatever rust did develop. And that's why you should swap your coolant in a timely fashion (and you better get rid of that expired Viagra too before you end up in the emergency room telling a very embarrassing story, just sayin').

So, how much does a coolant swap cost at a mainline Nissan dealer? About 200 bucks, broken down into about $170 in labor, and 30ish for the fluid. The GT-R just uses standard Nissan coolant, nothing special and expensive. Again, like I talked about in the oil change post, you can DIY these jobs to save you a bundle on labor as long as you know what you're doing. Here's a guide for you resourceful and awesome people who want to do so:

It's important to mention right now that there's another alternative to standard water-based coolants – the so-called waterless coolants like Evans NPG. I've never used them myself but have talked to several people who swear by them. They have several advantages over regular coolants – no need for periodic flushes, less pressure in the system (in theory less stress on hoses), no corrosion due to no water, etc. - in exchange for a higher cost for the initial replacement. After that initial replacement though you'll never have to swap fluids again so in theory it saves in the long run. A lot of people don't keep their cars long enough to make the higher cost of waterless coolant worth it but for gearheads who hang on to their cars it's worth considering - which is why I'm thinking of going with waterless coolant for my R32 once the fluids are being put in. I skipped it for the R35 this time since I hadn't done enough research yet to feel safe taking the plunge.

On to the differential fluid swap. With all those gears whirling around inside and working hard to deliver the power efficiently to all four wheels to give the GT-R its famed explosive acceleration and faster-than-electricity cornering you'll want to keep your front and rear diffs all nice and lubricated for maximum fun-making.

The differential fluid change is normally done at the same intervals as the trans fluid change. Mine happened at different times because of the build my car went through where the transmission was rebuilt and therefore had a fluid change then. Having mentioned that they normally happen at the same time I'd like to make a clarification on the transmission fluid intervals I gave in my last Maintenance Log post. Back then I said the interval was 18,000 miles by mileage and that's still correct but that's for a CBA or 2009-2011 car like mine. The later generation DBA R35s (2012-2016) - and presumably the 2017s as well, though I haven't seen the manual for that yet to say for sure - extended the interval to 36,000 miles or 36 months which I didn't know at the time of that post so I've since corrected my previous article to reflect this new info. The diff change interval should therefore be done as well at 18,000 miles/18 months or 36,000 miles/36 months depending on your car's model year. Of course, like any maintenance recommendation these are only guidelines and heavy use, especially on track, will need more frequent changes - so consult your dealer or a knowledgeable expert if you use or abuse your car more than normal.

To do this at the dealer is pricey even when you stick to Nissan's OEM oil – about $280 in labor plus about $390 in fluids means you pay just under seven hundred dollars every time you do this. If you're the DIY sort, here's a good guide to help you out:

And that's it for this Maintenance Log. Coming up in the next installment I'll talk about a very expensive but extremely important service – a full brake job. Check back to find out how many body parts I have to pawn for that service!

Cost summary for part 2:
Coolant swap - ~ $200 through a dealer
~ $ 30+ if DIY

Transmission fluid change - ~$670 through a dealer
~$400 if DIY


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