Oil change frequency

I have a 1997 Mercedes-benz C180 automatic with 129,000 miles on the clock, which I've owned for the past eight years. I change the oil and filter every 3000 miles, along with the transmission fluid (but not the filter). I also use an engine restorer/lubricant. The oil I generally use is Castrol 10W-40/15W-40, but I have now changed it to Shell Helix 10W-40 synthetic HX7 (MB approved 229.3).

The vehicle has not had any major problems. The last issue was a faulty crank sensor and the temperature sender has also been replaced. The radiator was changed after the lugs broke, but my local garage says this is a common fault.

My garage says I do not need to change the oil and filter, along with the auto fluid, every 3000 miles. What is your opinion? A Wray

While changing the engine oil at 3000-mile intervals will not do any harm, modern oils will certainly cover a much greater mileage before any deterioration will take place. You do not mention your annual mileage, but the time factor should also be taken into consideration, and changing the oil annually even at 3000 miles would not be considered excessive. However, I would be less inclined to replace the transmission fluid at such regular intervals. Although this should do no harm, the benefits would be minimal.

Given such regular oil changes, I would be less inclined to add a restorer in the engine oil, in case the cumulative effect of the product begins to become detrimental to the engine. You do not mention which product you use, so I cannot comment on the effects of this.