#ASKADE - JUNE

My vehicle has been filled with substandard oil. Should a premium product be used as a top-up, or will the existing oil negate the impact? Matthew Ball, Peterborough. (BEST QUESTION)

Oils of different performance levels should never be mixed. If you’ve got something in an engine which is below par, you’re never going to top it up to a level which is acceptable. Topping up with a better product will temporarily give you enough volume of product in an engine to keep you moving. But the oil should be completely drained at the first opportunity and replenished with a product at the performance level recommended by the OEM.

When will Euro 6 lubricants come into effect and how much more stringent are the emission regulations going to be with them in comparison to Euro 5 lubricants? Kev Davies

ADE:

Lubricants designed for Euro 6 compliant engines are already in the market place and have been for the best part of two years. There are stricter after-treatment device controls in Euro 6 engines compared to Euro 5 engines. It’s about reducing particulate matter and reducing levels of NO_x gases even further.  There is a jump in the severity of treating the exhaust gases from Euro 5 to Euro 6, but the technology has been well tried and tested and lubricant technology is already in the market place contributing to after-treatment efficiency and longevity.

If I have a car with a modern after-treatment device fitted such as a DPF, is there any harm in topping up between service intervals with a product which may not be suitable for that after-treatment device? Matthew Simmons, Birmingham

If a vehicle is fitted with an after-treatment device such as a DPF, topping up with a product not suitable during its service life will impair the performance of the lubricant that is in there and potentially have a detrimental effect on the performance of the after-treatment device.  For example, if you have a lubricant which is designed with the correct level of ash to not block DPFs and allow them to regenerate effectively during the service life and you add to that a product which has a higher level of ash than required, that ash will start to accumulate in the DPF. It could result in an early visit to your local garage.