Reddit mentions of Premium C8 MCT Oil | Boosts Ketones 3X More Than Other MCTs | Highest Purity C8 MCT Available 99.8% | Paleo & Vegan Friendly | Gluten Free | Pure Caprylic Acid | Ketosource® (35.2oz)

Actually, purely due to taste reasons, I generally advise against going with an extra-virgin option in favour of a lighter olive oil. However, I suppose if you do want to use purer versions, it wouldn't strictly be necessary to add the oil to the shakes - you could instead have a tofu + EVOO mix or even add the oil into coffee or something. Unfortunately, as I generally recommend lighter versions for taste reasons, and myself use an MCT/coconut mix (with a little flax or algal oil for omega 3s), I don't have much knowledge on good olive oils.

What is good, though, are ones in non-clear bottles, ideally that have been kept refrigerated, and perhaps with some added vitamin E (or other antioxidants) to minimise risk of oxidation. When it comes to oxidation, it's only really the PUFA content you have to pay attention to - olive is one of the better ones for this purpose, but still isn't ideal. In terms of optimising omegas, MCT/coconut is probably best here.

When it comes to MCT oils, there are various ones I tend to recommend. The most budget oil I recommend but still trust is this one. It's gone up in price recently, but is still competitively priced, and Mutant are a reliable brand. It's somewhat difficult to find the C8/C10 ratio, but if you look here and click on 'MUTANT MCT OIL' in supplement facts, a table pops up.

This shows in the top table that 15ml contains 14g of fats (density of MCT oil is 0.93-0.96g per ml, so 15ml translates to 13.95-14.4g so rounding would take this to the 14g - a good sign). You can also see at the bottom that this is broken down into 9.8g of C8 and 4.2g of C10, so there will be extremely minimal levels of C6 (which can cause GI distress) or C12 (which while extremely healthy isn't digested like MCTs for keto purposes).

The fact there is a breakdown and the oil is by a reputable brand means I am confident in its quality. Buying four bottles gets the price down to £18.19 per 946ml, which is £19.23/l (~€21.60/l). I haven't heard of the brand /u/ultraweaklisk linked, so I can't comment on how good it is unfortunately.

Another oil I recommend is the one you linked. Bulletproof are well-known for high-quality products, and specialise in MCT oils too, with both a C8/C10 mix like you linked, and a pure C8 oil (which some believe is better). Unfortunately, they keep the exact ratios of C8/C10 a secret, but I have no doubt they are reputable. The one you linked gives 2838ml for $80.88, which works out to $28.50/l or ~€24.84/l. I haven't checked postage (which may change things), but it's not too much more expensive than the Mutant option with just product price.

If you're wanting a pure C8 oil though, whilst Bulletproof's Brain Octane is no doubt a quality product, the price point is higher than an equally good one (which I use myself). When it comes to C8, some people swear by it and others don't feel much different from a typical MCT oil - personally, I can feel the difference when I take ~15ml per shake, though I don't really feel much on normal MCT oil. Anyway, the one I use is this one. It's a fair bit more pricy than the C8/C10 mixes, coming in at £29.66/l (~€33.32/l), but if you're wanting an isolated C8, it's probably your best bet. Of note, some of that C8 oil is sourced from palm oil, but as per the questions on the product's amazon page, this palm oil is sustainable and has been certified by the RSPO (Roundtable on Sustainable Palm Oil).

One potential option to all of this, if you're concerned about price per serving/quality of coconut/MCT oils, get GI distress from them in high amounts or dislike the omega content of olive oil would be a high-oleic algal oil. Now the company I'm aware of that do this will, I believe, generally only sell to companies, but you may be able to negotitate with them if buying something like 25 litres.

The relevant page is this one. If you scroll down to the fatty acid compositions table, you will see that their oil is 93% monounsaturated, 4% saturated and only 1.9% polyunsaturated. Even assuming you're using 200 grams of this stuff per day, at most that's giving you 3.8g of PUFA. Even at 400g for ~4000 calories per day, you're looking at 7.6g of PUFA.

Now unfortunately, I can not find a reference to the omega 3 to omega 6 ratio. I can make some predictions though, based on previous correspondence I've had with the company regarding their algal flour. Before I get into this though, it's important to note this is all assumptions, as they do not derive the oil with the same method as the flour, so there may be different ratios.

Anyway, with the flour, the fatty acids are, by mass, 11.6% omega 6 and 1.2% omega 3 (I can provide the document listing the breakdown if you are interested). From the above, we see omega 3 makes up 9.375% of PUFA whilst omega 6 makes up 90.625% of PUFA). If we translate this to the algal oil, and assume 100g of algal oil contains 98.9g of fat (as per the sum of values in the oil page's fatty acid breakdown) (and hence 98.9*9 = 890.1 calories), we can work out what would be required to get 4000 calories from KetoGenesis (I'll assume unflavoured vegan for calculation purposes):

Three servings of unflavoured vegan KetoGenesis = 444kcal, 0.7g SFA, 0 MUFA, 0 total PUFA, 0g omega 6, 0g omega 3.

400 grams of Algawise algal oil = 3560.4kcal, 16g SFA, 372g MUFA, 7.6g PUFA, 6.8875g omega 6, 0.7125g omega 3.

Total: 4004.4kcal, 16.7g SFA, 372g MUFA, 7.6g PUFA, 6.8875g omega 6, 0.7125g omega 3.

The algal oil is providing enough omega 3 in the forms of DHA and EPA that the capsules won't be necessary if you're using 400g of the algal oil daily. You may want to lower that slightly and include some flaxseeds or flax oil to make the omega 3 to omega 6 ratio closer to 1:1, but this seems to be the best way to go if you want to avoid coconut/MCT.

If you're interested in this route, I can request more details from Algavia about the oil (eg cost, accurate fatty acid breakdown, etc).

Hope this helps :)