In "game.log" i see a lot of information like this: 00:04:31.514 : <ERROR> [fs] Failed to open file "/def/vehicle/truck/scania.r/accessory/b_grill/shape10.sii" in the read_only mode
What I can do with it? I have no experiences with modding.

You can choose Scania R
and see "game.log" that mod makes a mistake.
The only method without a new career.
be sure to save a copy.

I download this mod http://ets2.lt/en/scania-multi-mod/ but i can´t drive Scania R. I tried to start new carrer with this mod only, but after I made tuning, my game fell down. I tried it second time with fix but the problem is still there. I have no idea what I have to do.

Give this fix at the end as the last mod.
Maybe mod skin-conflict.

Thanks, red mirror resolved, but my second problem with Scania R is still there. When I sit to it and want to start it, game fall down. I tried to start new carrier and i have there same problem.

As promised this should help
http://sharemods.com/4mqzklft7vkh/zzredmirrorfix.scs.html :)
Will help on the red mirror and AI traffic.

Thanks :)
This Scania is from version 1.8.x unfortunately with 1.9.x it has a lot of problems, skins and mods :(

If you do not improve the red mirrors in the next patch, I'll give you a link.
Please understand I can not do without permission.
GREAT Scania :)