I know this is a not quite the MX5 experts type question, but there are is a lot of knowledge here…
WD-40 is a contact cleaner, and a water displacer. So it is good for, well,… cleaning and shifting water off damp surfaces.
But, it is also said to attract water, and therefore actually causes rust to form in the long term as it saturates and then bleeds dampness onto the surfaces it is meant to be protecting. Also over time it thickens to a gum, and thus stops fine mechanisms working (eg small springs and catches - gun mechanisms, watches, etc).
So I tend never to use it, except for cleaning. I have penetrating oil sprays I use to lubricate.
My question is, am I being overly cautious? Are silicon sprays, and penetrating oils just as bad?
I use it for squeaky hinges stubborn rusty screws/bolts although I have some stuff like plus gas for those too. The large can I have I mainly use to spray over the coilovers on the five, in 4 years (on the other NC) it kept them in a new looking condition, no corrosion. I don’t use it on electrical connections though.
The original WD40 is specifically a water dispersant (WD number 40).
It also happens to be quite a good insulator, so was ideal on the old Austin/Morris minis to spray all over the distributor and ignition leads, thus allowing them to work reliably (well, almost) in the rain.
It also turns to clogging glue, so is utterly useless in locks and small moving parts.
As a good insulator with a good film strength it is also death to electrical contacts, especially to low voltage low current devices such as CAS and knock sensors.
To “clean” an electrical contact use a proper lubricating contact cleaner such as Servisol Super 10, well proven for decades. I’ve used it since the 1960s, most of the time with surprisingly long lasting success. Usually, if Servisol does not cure a bad connection, there is a significant mechanical problem, not mere oxidation or wear.
I do still have a can of WD40. It still has its uses around the place and as well as the advertised main use it’s very good at removing glue left behind from sticky labels!
However, over the last few years I’ve preferred GT85 spray which works better overall (and smells nicer as a bonus). It’s actually owned by the same company as WD40.
I still have WD40 but only use it to clean off scale from taps, shower heads and also sticky labels.
I use Contact Cleaner for doing just that.
Kano Kroil for penetrating oil, better than all others as far as I’m concerned but a tad costly but worth the money. I have used this a lot on my 1925 stationary engine, invaluable when bolts have rusted over the past 100 years.
I use brake cleaner or Isopropyl Alcohol as degreaser for most things, best is Isopropyl Alcohol I find.
NEVER USE WD40 ON RUBBER SEALS!!! they can swell up and go soft and yucky! I’ve got the T shirt and video for master cyllnder rubbers.
If used on ignition parts my experience shows it may work short term but then dirt sticks to the items and it gets worse. Better to replace parts if they are starting to breakdown.
For penetrating use I find a mixture of Auto transmission fluid (or PS fluid) and acetone (nail varnish remover) to be a cheap and effective fix. I mix it as needed as the acetone seems to separate out and maybe evaporate over a period of time. I also use a small syringe to get it where it’s needed rather than using a spray which tends to go everywhere.
Acetone… I used some once to clean up oil that had been sprayed onto somewhere it shouldn’t have been.
Big mistake. Plastic turned brittle and crumbled and a solenoid swelled and stopped working.
Funny how wd40 has become the universal lubricant found in every home and toolbox for squeaky hinges to seized joints. Yet, is shunned by everyone who knows what they are doing. I do wonder how much is anecdotal; that said, I bought a gallon of wd40 about 15 years ago, and still have a gallon of it left.
Please don’t use it to speed up windows. It will work for a very short while but then it’ll wash away the remains of the white lithium grease that needed to be there.
Had its day big time, far better products on the market for the jobs needed, old schoolers fly the flag and still use it for everything causing bigger problems on these roadsters, its ok if used for the right things , but not much, not a product I keep on the self to help sort these roadsters.
M-m
I tend to favour GT85 which can be misused for all the same purposes as WD40, and contains PTFE which makes me think it’s more likely to retain some lubricating function when it dries out.