Your Lubrication Questions Answered
If you top up your engine with a mineral oil when it is filled with a synthetic (or vice versa) will they mix?
Ade’s Answer:
The quick answer is ‘yes’.
Mineral oil based engine oils and synthetic based engine oils will mix together if there is an urgent
need to top the oil up, especially if it is showing low on the dipstick or an oil level light has illuminated. This will safeguard the engine temporarily from any oil starvation issues.
The next question to ask, in this instance, is whether the oil is the correct one for the engine? The manufacturer of the engine will specify the performance level of the oil and that is the crucial factor. Irrespective of whether the oil is mineral based or synthetic based, bear in mind that if you’re topping up with oil that has a lower specification than the one currently in there, the overall performance level will
be lower than the one specified by the manufacturer. This could potentially lead to issues further down the line.
If you’re topping up in an emergency, ensure that as soon as convenient, the oil is fully changed to the correct product, as this will eliminate any risk. If, however, you’re confident that the oil is equivalent or better, you can make a judgement. If there is any doubt, it is worthwhile contacting your motor factor or
an oil expert for advice.
