'94 VW Jetta Oil Light

[bonz]

Oil light has been coming on recently at random. Several service technicians believe we should start by changing oil grade from 10W30 to 15W40. If this does not remedy the concern, then I've been advised to replace the two oil pressure sensing switches. Is there a site that would have a schematic of this engine type. " 1.8 L " 4speed auto. Any input would be much appreciated. This will be my first time availing of such a format. Please advise if there is certain rules or etiquitte I should be aware of.
Looking for advise in NL
Bonz

[The General]

In many cases, the oil sending unit/sensor or it's connector are faulty . I doubt that changing the grade of the oil will fix anything.