The sun is out and its nice and hot, so why should we prepare for winter, just for that reason, the sun is out and many jobs take little time, and its nicer to work on vehicles with the sun on us.
Check the underbody, clean any rust and underseal any rusting areas, likewise treat any prone areas such as the radiator lower crossmember or other vulnerable area with treatments such as Waxoyl or similar. Grease any suspension joints and propshaft joints while you are there, pump grease into them intil the old is expelled and the new grease emerges, do this once again in about a months time to ensure all joints have a full capacity of new, fresh grease. While underneath you can smear any moving parts with grease, such as any handbrake cables or mechanisms. If you have a leaf sprung vehicle you can lay newspaper under the springs and paint with engine oil, force this in well, and absolutely lather them in oil to flully lubricate them. Spray a little silicone oil onto rubber bushes ro rejeuvenate them.
Remove any underbody trays or protection and clean and degrease them, paint them with a good industrial paint or other good paints such as Hammerite smooth, dirt will literally drop off with the application of a hosepipe.
Examine the vehicle bodywork for scratches and repair them, much easier to to paintwork in summer. Open all the doors, boot, and bonnet while the greasegun is out, put a little on your finger and work it well into each hinge, force it in so it penetrates. Look at any door stay, the metal strip which stops it opening too wide, smear a little on the top and bottom of the door stays and open and close the doors a few times to distribute it.
Spray a little WD40 into your door locks through the key hole, even if you have central locking, leave for about an hour for it to evaporate and you now have moisture free and clean locks, now use a light oil such as 3 in 1 and force some into the locks through the keyhole, your locks will not freeze up now. Look at the end of the door and note the door latch mechanism, put a little light machine oil in here to lubricate the latch mechanism, don't worry about using too much as this will drip into the bottom of the door and rustproof it.
Open each door and examine the door rubber, clean with a good trim cleaner suitable for rubber, note how much much is removed, then buff, do this a couple of times; likewise, note where the door rubbers contact the bodywork and polish this area a couple of times, when everyones doors freeze up and will not open, yours will.
Clean all the interior glass, i prefer Auto Glym glass cleaner as it is very good, do this and you will notice an immediate difference in visibility. Treat the outside of the glass with a water repellent such as Rainex or similar, apply at least two coats to side windows, and more on the windscreen and rear windows, repeat this weekly as this will build up a nice thick coating on the windows prior to winter, then watch the water run off without using your wipers. Rainex can also be used on plastic, other treatments cannot, if you have glass head and fog lights then give them several coats as well, if you have plastic lenses then use a brand such as Rainex which is safe on plastic and give all the front and rear lights several coats. When winter comes and everyone's headlights look like candles in brown paper bags, yours will stay clean and much brighter, you can see and also be seen.
If you have a rear door mounted, or even bonnet mounted spare wheel, take this off, apply several good coats of polish into these areas you cannot normally do, this will help it stay clean in thease areas. Check the spare wheel and tyre, overinflate the tyre and polish the wheel if its an alloy rim, of you have a vinyl cover you can clean the inside and apply vinyl suitable trim cleaner to the outside, apply several coats as it absorbs it in summer as it is dry, then buff to a nice finish. Refit the wheel to the carrier and apply a little copper grease to the threads of the studs or nuts do they come off easily when they are needed, of you have a lock you can clean and lubricate this also.
Check the vehicles wheels if you have alloys, thoroughly clean until they shine, if you have any chips in the lacquer then apply clear nail polish and build it back up to the height if the surrounding lacquer, wet flat once hard using 1200 wet and dry paper, wet. Dry the wheel and polish it inside and out, this will prevent dirt and brake dust from sticking.
If you have a sunroof it will undoubtedly be used at this time of year, apply a little silicone grease to all moving parts and any accessible mechanisms, using the sunroof will distribute the grease, likewise clean any sealing rubbers in the same way as your doors, removing any dirt will prevent water seepage in the winter.
Clean any plastic trims with a silicone cleaner, plastic trims dry out and they fade, repeat this several times during the dry weather and the trim will absorb the silicone cleaner and stay much nicer for much longer
Take the time to polish your car, if you can do it every week for the next few weeks then all the better, i prefer Auto Glym as it works out cheaper in the long run, and gives a very nice and long lasting finish, after the first three or so coats it begins to build up rapidly and you use very little to polish the vehicle, so works out cheaper in the long run. If you can get several coats on now it will protect the vehicles paintwork right through the winter, even if you do a couple of panels periodically it does not matter, just as long as you build it up.
Take the opportunity to do routine jobs such as cleaning the engine, thoroughly degrease and clean, backflush any radiators from inside the engine compartment using a hosepipe, this will remove any dirt, insects, and mud from the various radiators and intercoolers and make them more efficient.
If your vehicle is coming up for its anti-freeze change every two years (normal anti-freeze) or four or five years (long life anti-freeze) then do it now, drain the cooling system and remove any pipes and flush through with a hosepipe, remembering to set any heaters to the hot position so water flows through the now open valves. Replace the pipes, fill with plain water and run the vehicle to swill it all out, drain, and refill with anti-freeze, then top up with water; if you get wet then who cares as you will soon be dry again.
Take the opportunity to replace any other periodical fluids which require replacement such as brake fluid which requires changing every two years, any ATF on automatic transmissioned vehicles, and replace any air conditioning / climate control gases as its summer and cheaper now everyone wants theirs doing.