Don't use Armorall. It seems it attracts dirt which works into the pores of the dash and aggravates the problem. Use 303 or other UV protectant regularly.

Keep dash clean: use a cloth dampened with water on the dash when not hot from sun.

Don't use Baby Wipes. Women love this one. It has alcohol which speeds up the dash drying and hardening.

Feed the dash. Use a product that keeps the plastic from hardening in the first place. Mercedes parts department has such a product.

Never ever apply anything to the dash when it is hot.

Watch out for car washes applying "interior dressings".

Haasman

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'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)