Just had my car serviced and the garage advised i needed my top strut mount replacing.

Do i need this doing ASAP? it only rattles at low speed on a full left hand lock, normal driving conditions it doesnt seem to make a sound.

When i bought the car i noticed it looked like someone had been taking the top mount off recently (my guess is to bodge it with grease) and it looked crossthreaded.

The car had a full MOT when i bought it with no advisories.

What can i expect to pay for a replacement?