Fully Synthetic Oil Mixing With Other Oil

[foxyferret]

My daughters car Peugeot 107 ran out of oil as she had forgotten to check it. All the garage had was 15/40 fully synthetic oil. Does she have to continue with this as she has some multi grade oil at home but not sure you can mix these two together. Also, now the fully synthetic is in the car, can she top up with semi synthetic or not? I had a quick look on Google but there seems to be conflicting advice. Any help would be welcome.

[Buenchico]

My attitude to motor oil is generally that, if it looks wet and greasy, I'll just chuck it in. I'm fairly sure that my car's engine has a mix of 5w30 and10w40 oils in it, possibly both conventional and synthetic. So I wouldn't worry too much about the oil in the engine of your daughter's car.

However, as there's currently fully synthetic (and therefore better quality) oil in her car's engine, it would seem sensible to me to try to stick to using it. Even so though, using semi synthetic oil is unlikely to cause any harm.

https://blog.amsoil.com/can-i-mix-synthetic-and-conventional-oil/

[Hopkirk]

Surely semi synthetic means a mix of the two. That proves it's OK to mix them.

[douglas9401]

An old mechanic friend once said "Ile's ile". :-)

[foxyferret]

Many thanks all of you for your advice.

[richtee]

If the vehicle is less than 5 years old, I would use the oil recommended in the vehicle handbook at the next oil change. For an older vehicle, I would use 10/40 semi-synthetic- perfectly ok for this vehicle, and much cheaper than synthetic.

[davebro]

When you say "ran out of oil" I assume you mean it has used some & dropped below the indicated fill level? If it ran out of oil completely that indicates a serious problem.

[foxyferret]

The red warning light came on but fortunately she was close to a garage. It was entirely her fault for not checking it regularly. I have advised her to remember to check oil, tyres etc in a regular basis.

[Hopkirk]

They think that is what Dads are for.

[foxyferret]

Or moms in my case

[Hopkirk]

Oops, sorry

[foxyferret]

No probs Hopkirk