Dinitrol, Mercasol or Waxoyl


New Member
I have decided to get the underside of the Spyder treated as I live by the sea and I use it occasionally through the winter.
I have some quotes from these chaps www.CarRustTreatment.co.uk who have an outlet at Patchway in Bristol, and who describe the process:

"............. includes the complete treatment of the under body, chassis, axles, suspension components along with door cavities and sill areas. The treatment is completed by a fully trained operative, your vehicle will be fully cleaned, dried and prepared prior to its treatment which includes the removal of loose rust to ensure we apply treatment to a solid material and the removal of plastic arch liners if required. The treatment is applied via compressor to ensure an even and thorough coating. We will require your car from 9am-3pm."

Dinitrol ML, 1000 and 4951 - £560
Mercasol 1, 2 and 3 - £495
Waxoyl - £480

So, any thoughts on the most effective treatment, also does this seem a bit steep for 6 hours max work? Or is there anywhere else in the southwest that anyone has had dealings with and could recommend?


I personally have used Waxoyl for years, and if applied correctly it is marvellous stuff provide it attention to detail is taken.

Having read your post, the thing that would bother me is the timescale which includes the both the cleaning and application process. If after removing "all" the loose rust paint etc. they pressure wash your car underneath, there is no way all the dampness will be gone in the time you are talking about before application of the Waxoyl. The job is better done when the weather is hot or in a heated garage, and the car allowed to dry thouroghly after cleaning. This can take several days. If you don't do this, water that has tracked into seams and joints will be trapped and corrosion will continue underneath the Waxoyl layer.
Waxoyl is a very good product, but it doesn't last, and will need re applying at regular intervals. I use products from this co https://www.rust.co.uk/ and for a longer term solution I would recommend that you investigate this.
Thanks chaps. it does appear on further research that Dinitrol is the way to go nowadays. however as mentioned above, a six hour turn around is a bit keen!


Centenary Club
A few cars I have owned have had dinotrol from new, 79 Opel Ascona and my current 82 Giulietta both despite their reputations showed no sign on the dreaded tin worm. I will be having the Fulvia done next Spring once the weather warms up and the SZ will be done as soon as it is out of the paintshop. You need to keep doing it to maintain the protection but no where near as often as wax oil which just melts away over time