Oil pressure sender for '89 MC-1 engine...and other switches

[Gerard]

Hi!

It's the week for getting new sensors and connectors for my project car.
:) I found my oil pressure sender in a box in the trunk and it's in a
filthy condition so I'm not even going to bother cleaning and re-using
it.

I looked in ETKA now and see 2 items listed.

  0-5/0.3bar M10x1 2-pin plain oil press sender 035 919 561
  0-5/1,8bar M10x1 2-pin black oil press sender 035 919 561 A

My original is too filthy to spot whether is a black indicating mark on
it or not. I'd like to know which one to use.

The bought a new oil pressure switch on Monday for $3.80. It matched the
part number on the original and it had a white marker. This is,
according to ETKA, a 1.8 bar switch. The other in ETKA is a 0.25 Bar.
Matches nicely with the items listed above, so am I correct in thinking
that I need the black item and not the plain?

This was probably a silly question, but I'd rather confirm before buying
someone that's incorrect.

Also, they quoted around $25 for this sender at the local NAPA-like
store, but ofcourse not sure if it was for a "plain" or a "black". Is
that a good price or not?

Is it possible to get a aftermarket replacement switch that goes in the
brake master cylinder on the Audi 200? I disconnected mine years ago,
probably 'cos the bomb died, but just want to know if these are easily
sourced just in case I have a problem with it.

Any other sensors worth replacing on a 13 year old car? So far I have
radiator switch, multi-function switch, oil pressure switch. I will be
buying a oil pressure sender, a oil temp sender and the switch on the
water union on the cylinder head, not the 4-pin but something marked
"97/110 2-pin plain thermo switch (054 919 369 B)" in ETKA. There is a
1-pin below the union, directory in the block (or head, I don't recall).
What is this for?

Thanks.

G.