Synthetic VS Regular Engine Oil

Hello All

I have a 1997 528i automatic with 100KMS on the odometer. I am due for an oil/filter change and need some advice from fellow BMW owners/mechanics/enthusiasts.

The car currently has and always has had regular engine oil in it, I am considering switching to synthetic oil.

Questions:
1. Is there any harm is switching to synthetic oil?

2. What are the pros/cons?

3. If I do switch to synthetic, how frequently should the oil be changed?

4. What grade should be used? (The weather up here is Canada is starting to warm up and over the next 3 to 4 months should be between -5C and +20C).

Thanks in advance for your replies and happy motoring.

Oops...the odometer has 100,000 KMS.

i would not change over to synthetic with 100km on odometer it's gonna eat all of you'r gaskets in the engine happened to me on 2 different cars!!!
belive me

Dont mix the 2 oils.
Keep the ragular oil in it
Chage it every 3k-5- miles.
If you change to synthetic change it about every 15k

Ide use some 10w-30