Synthetic and semi synthetic; help please?

[malcolm]

So I realise that this is a bit non E Type related, but I know there are plenty of experts on here who can help. My new F Type I've discovered has just had its oil replaced with semi synthetic. According to the book, it should have fully synthetic. Questions:
1) does it make much difference, semi or fully synthetic?
2) can I top it up with full synthetic and thus mix it?
3) do I need to drain and start again?

[abowie]

1. If you believe the manufacturers, probably yes.
2. Yes but it will still contain some mineral oil components, which may degrade more quickly than the fully synthetic molecules.
3. Personally I'd just change the oil earlier than normal and put in fully synthetic if you believe 1.

The general recommendation for modern high performance engines seems to be fully synthetic oil. There are as many opinions about this as there are posters on the internet, but to me if the oil is more resistant to degradation and performs better in high demand applications I would use it when recommended.

[malcolm]

Thanks Andrew. I'll change it when the time comes when I can drive it properly again! (Damn Covid)
Certainly by May when it's due for my annual track day.

[Heuer]

Follow the manufacturers instructions to the letter. For our 993, Porsche specify Mobil 1 and I have only once deviated from that at the suggestion of a well known specialist based on cost. The result was an odd gurgling noise from the engine until it fully warmed up. Sounded like a cross between severe indigestion and blowing bubbles underwater. Took it back and after much head scratching they decided, at my suggestion, to replace the generic bulk oil with Mobil 1. It cured the problem instantly and they have only used Mobil 1 in all Porsche cars since.

[malcolm]

Wow. Thanks David. Sounds like I should change it sooner rather than later. Presumably I'll have to change the filter as well, as there will be oil in that. Shame, both changed just before I got the car! Why did they have to save a few quid and put the wrong stuff in?

[malcolm]

So on that well considered advice, car booked in for oil and filter change next wednesday.
Thanks

[chrisfell]

I have been using semi synth for several years. Despite the longer life of this oil, I always change every 3,000 miles or less. And I change the filter every time even though that is every other change on the original schedule. I buy the oil in 20l barrels and the filters four at a time.

Three oil and filter changes every two years, on average.

[MarkRado]

Yep, frequent oil-and filter changes is the way to go. I choose oils (only mineral) on basis of viscosity for classic cars, but I guess this is an endless debate. My E's engine runs definitely more quiet with new 20W50 even after only 3000 miles young oil.

[malcolm]

Mark and Chris, just to point out that my post was about oil for an F Type, NOT for my E.

[MarkRado]

Hi Malcolm,
yes I was aware that its about the F. Basically this is my opinion: correct oil spec, frequent changes, never mind the brand. But I have to admit that I have stayed with the Jaguar recommened Castrol 5W30 on my XJ8 (but only because I hope that I can escape the Nikasil liner death).By the way I dont think semi synthetic is a problem until the next change as long as you dont go racing

[malcolm]

By the way I dont think semi synthetic is a problem until the next change as long as you dont go racing

Thanks Mark; but I will be, in May, at Goodwood - subject to lockdown! So might as well change the oil now.

[MarkRado]