dash mat = more problems?

[george graves]

When the dash on my restoration car cracks I'll just get get a new one from BMW. It should be good for at least another 20 years.

I thought they were NLA? - or like $1200 or something?

If someone wants to - make a replacement dash OE, Carbon fiber, or simulated leather......profit. (that new CF-like fabric in the new BMW's is interesting)

[long tall eta]

i put olive oil on my dash and my wife said ( and you question me about vinigar in the medicine cabinet )

[george graves]

Way too much info....

[nando]

Oh okay, good to know you know everything over here. How bout you tell me how oil stops something from getting damaged by the sun.

when you finish grade 10, then we can talk.

[jlevie]

I thought they were NLA? - or like $1200 or something?

They are still available and they do list for $1200. Probably not something you'd do for the average E30, but if you are putting $7-8K into a restoration it makes more sense.

[bmwstephen]

In all seriousness I am torn on the subject.

I drove my car yesterday for a while in direct sunlight without having the dash mat on. Suffice to say, the dash was cooler to the touch without the mat. I guess the mat ends up trapping the heat underneeath it above the dash.

Now goes the question of what the leading factor to dash cracks are. UV exposure or heat

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[nando]

I would just use one of those sun shield things.

[dnguyen1963]

Okay...here is the "theory" behind using oil on your dash...UV rays from the sun is the major reason for the damage on your dash (not so much heat, but remember UV rays have so much more energy and that energy will convert to heat). When UV rays are shine on your dash it must be absorbed by some other materials. Too much UV absorption will start to cause the bonds in the plastic material to break, hence dash-cracking. Oil (especially olive oil) with many double bonds, which can absorb UV rays nicely, can absorb the UV rays instead of the dash. However, the best method of preventing dash-crack is nor letting dash expose to UV rays. Therefore, the most economical and sensible method is to use a wind shield reflector. BTW, sun screen lotion works much better than oil because it is designed to absorb UV rays.

[jlevie]

In all seriousness I am torn on the subject.

I drove my car yesterday for a while in direct sunlight without having the dash mat on. Suffice to say, the dash was cooler to the touch without the mat. I guess the mat ends up trapping the heat underneeath it above the dash.

Now goes the question of what the leading factor to dash cracks are. UV exposure or heat

Both. Heat alone causes loss of plasticizer, making the plastic become brittle. UV causes changes in the chemical structure.

[nando]

one major reason I wouldn't use food based oil is because it will break down. I can't imagine it smells all that great after a few years.

[dnguyen1963]

Both. Heat alone causes loss of plasticizer, making the plastic become brittle. UV causes changes in the chemical structure.

Not quite, Jim. Most of the leaching plasticizers are comtaminants from the polymerization process and are present in small amount. The "plastic" smell that are present in new cars are derived from these contaminants. The free plasticizers do not stay in the dash for more than a few years. Heat, on the other hand, causes expansion and contraction of the dash. Repetitions of these cycles will eventually lead to cracks. UV rays speed up this process because it will degrade the plastic, thus, causing many weak-points in the dash.

[Exodus_2pt0]

one major reason I wouldn't use food based oil is because it will break down. I can't imagine it smells all that great after a few years.

^ This.

I have a crack free dash, came in my car that came out of a field.

My theory? No one every tried to "protect" it by putting crap on it. Result? No cracks.

I'm afraid to put ANYTHING on my crack free dash. She gets wiped down with a damp rag on occasion.