Swapping from fully synth engine oil to semi - is it ok?

[haggis]

The bike (tuono) is due an oil change, and I'm removing/replacing the old oil tank while I'm at it.

Last time I serviced it, I used Castrol GPS fully synth. But I've ordered and received Mobil 1 this time believing both were semi synthetic, which the Mobil is. So technically a downgrade.

The more I read and research, the less sure I am it's ok to do this. Initially thought it was ok as long as you didn't mix fully with mineral. But now read that once you use fully synth it alters the wear patterns and you shouldn't go back.

Got the oil, filter, new tank, plugs etc ready to service before the GM7... But stalling til I get advice from someone who is knowledgeable and trustworthy, hence posting here, not the aprilia forum which is almost useless lol :help:

Come on u guys, save me here.

[Tomor]

Dunno. :)

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[DJ123]

Most engines will run either ok. But some will burn fully synth and vice a versa

[Bibio]

dont fret. the problems about fully synth were years ago and mostly caused shrinking of the rubber in the stem seals and a few other related problems. almost all engine oils that are branded as fully synthetic oil are indeed a mix. there are very very few fully ester synthetic oils on the market and they carry a huge price. car/bike/oil makers are aware of the problem caused years ago and most if not all have taken steps to insure that most of the oils on the market are able to mix with each other. a true fully synthetic oil will carry a warning on the label stating that it will not blend with other oils.

oils branded as fully synthetic will let you run longer oil change intervals than semi synthetic and thats about upshot of it.

the term 'synthetic oil' is very misleading anyway as one would assume that it's vegetable based man made oil when in fact most of the time its actually homogenised dino doo to create a more uniform molecule and because of this the makers are allowed to put 'synthetic' on the label. so i very much doubt that the castrol you were using was indeed a fully synthetic.

one of my favourite oils is Millers ZSS 10w40 (http://www.millersoils.co.uk/automotive/tds-automotive.asp?prodsegmentID=209&sector=Motorbike) and if you want more synthetic content then you just mix in Millers ZFS 10w40 (http://www.millersoils.co.uk/automotive/results-tds-auto.asp?SegmentID=408&market=Automotive) i have found that the ZFS is a bit thin on its own to use in twins. before i started to mess with oil mixing i spoke to Millers tech bod and he said its perfectly fine to do so and a lot of people do it. only reason i stopped using Millers was they changed to 4lt cans but kept the price the same so i switched to halfords own 10w40 semi synth which are still 5lt and easier to get a hold of.

[AJC]

I have always used halfords semi stuff in all my bikes but people keep saying to me the blade should be run on fully synth... I probably will do i as the difference in price isn't that huge. But does anyone think it will make all that huge a difference?, when I will be changing it every 3-3.5k miles anyways?

Talking of that, any oil suggestions. I was just going to find the best priced oil and filter set off ebay... Not that it needs it any time soon to be honest.

[Bibio]

cheep filters compared to expensive filters. its all down to the amount of material pleating in the filter. a cheep filter will have less pleating so less filter surface than a better quality one. think about it this way, take a cup of sand and pour it on a bit of paper 1mt x 1mt now take the same cup of sand and pour it onto a 1mt x 3mt piece of paper with there being more surface area you get less clogging.

personally i stick to OEM filters.

[AJC]

Sets I was looking at seemed to come with K&N filters which must be pretty decent, I hope :)

[nutzboutbikes]

Another vote here for OEM filters they are the only ones I use in the bike, both air & oil.
There is no problem going synthetic to semi it will have no ill effects the main thing is it is changed regular, I use Shell AX7 however I would have no issue using Mobil 1 its a top oil.

[haggis]

Y'see, that's the kind of answers I expected around here.
Mind fully at rest, thanks all. :)

Alan - I got an Aprilia oem filter for £14, then bought the oil at £26 which came with a free pattern filter. Not k&n, but another well known make. Either they are selling these at a loss or they ain't up to much. I'm not gonna be risking it.

[Bibio]

you got Mobil 1 for £26.. are you sure that its not Mobil extra 4T?

[SV650Racer]

Tuono needs 15/50w oil and synthetic is recommended.