car oil

I have a mercedes benz 190D production year 1988, at the moment i am using GALP oil (a Portuguese company) for my engine and i want to know if this oil is suitable for my engine, has the right parameters for my mercedes engine. thanks...

I am only familiar with API oil standards so not knowing where you are this may be of no use to you but a Mercedes diesel should use CI-4 rated 15w 40 oil with a Hengst or Mann filer element.

W123_W126 is correct.
Using a 15-W40 oil has more detergent for Desiel engines.
If you change your oil every 3 months any oil will work fine.
If you want to go for longer change periods I suggest Redline Oils, they can run an average of 8K-10K miles with out a change. Keep in mind that if you do use a Synthetic oil you still need to change your filter every 3k miles.

yes i 15-w40 oil is correct

API spec CI-4 is the correct oil to use as said above. Do not use regular motor oil as it is likely to lack some qualities CI-4 provides, such as
thermal stability, soot handling capability, acid neutralization ability, corrosion protection, and oxidation stability.
Diesel engines are very different and so is the oil they use in their crankcase. Regular gasoline engine motor oil is not designed to withstand the punishment a diesel engine can submit to it. Depending on the workload, standard motor oil may last only a matter of minutes before losing its integrity to properly lubricate.