Whoops, wrong kind of oil !!

ScouseMouse

Need some advice please folks. I have a 99 focus 1.6l PETROL and checked the oil level. It was at minimum so I put in a litre of 15w40 oil. Only after did I notice it was for DIESEL engines. So now the oil level is ok but with the wrong kind of oil. I rang my garage that looks after the car and the mechanic tells me diesel oil contains detergents that may damage the bearings so I should do an oil and filter change.

I told him I could do it myself so there is no benefit to him to bluff me. He said it is not urgent but should be done.

Does anyone else have an opinion?

Thanks in advance.

Jeff

bushy...

Its not that the detergents will damage anything , its that they might dislodge muck that MAY have built up.

patpark121

If you can change the oil yourself do it for piece of mind. 1 Litre shouldn't make it degrade too much in performance, it is more abraisive than petrol engine oil because of the extreme pressure the diesel operates under.

I regularly use 15W-40 oil to top up mine (petrol variant), but it should be noted, for the record ford recommend SAE 5W-30 oil. Or failing that 10W-40 or 5W-40.
Not being pedantic or otherwise.... it's in the manual.

IrishRover

I wouldn't worry about it too much. On a petrol engine car that has had its oil change intervals missed, or has been neglected somewhat, I do a complete oil change for diesel engine oil (because of the extra detergents) and run it for one or two thousand miles and have never had a problem since. One of of these engines, with over 130,000 miles, removing the cam covers and inspecting the cams showed the head was in excellent condition with perfectly clean golden coloured oil, and taking off the head showed no problems with pistons and bores. Whatever about the potential for damaging your engine, it's certainly not nearly as abrasive as an "engine oil flush" additive would be.

However, I would be uncomfortable about mixing grades of oil.
Also, the difference between max and min on your dipstick may be less than 1 litre, and overfilling with oil is bad. I you didn't wait long enough for all the oil to drain down into the sump, or were not on perfectly level ground, you may have got a falsely low reading on the dipstick.

As said, because you've mixed types of oil in it and may have slightly overfilled, I'd change for the correct grade as soon as is convenient, but I wouldn't be overly concerned about it.

Captain Slow IRL

any oil is better than no oil!

the detergents shouldn't pose any threat, but 15/40 is too high a viscosity rating to be putting into it - 5/30 is what you should replace the oil with should you do the oil service yourself