Hi
OMSL will not help here because that is for changing the number format for materials. Incase you want to have different number formats for the different types of materials, you can simply have material types different.
However, you mentioned taht all of them are of type HAWA and should not be changed
In this case you can use external number range for the materials, and make sure you have internally within the organisation defined the rules for assigning numbers to materials, like
1. Normal Parts: NP123456
2. Lubricant: LU123456
3. Accessories: AC123456
Please let us know in case this solution is feasible to you.
Regards
Vivek Singh