Conventional Vs. Synthetic Oil

[DieselScout]

Why do y'all prefer, conventional or synthetic oil and why?

I usually run Conventional Rotella 10w-30, but do to local availability, I used Synthetic Rotella 10w-30 on my last oil change.

[anders]

I run 5w-40 valvoline extreme synthetic turbo diesel oil, I used to run 5w-40 delo 400 synthetic. Both are great oils, I changed over to the valvoline because of availability. I run 5w-40 for many reasons, I have a personal “fleet” of boats, motorcycles, excavator, mowers, trucks, ect.. while the 5w-40 I don’t use in the bikes it gets used in everything else because of the wide viscosity range provided from being synthetic.

About a decade ago I did run 15w-40 delo 400, never any issues with it, changed to synthetic because of needing the expanded viscosity range.

[v8volvo]

I do pretty much the same thing. The oil I use in everything is 0W40 Rotella T6, sometimes 5W40. Any good diesel rated 5W40 synthetic should be a great choice, the ones Anders named, or Rotella, or some folks like Mobil 1 Delvac or TDT. There are probably others. All are pretty reasonably priced at this point and easy to find, and with such a wide viscosity spread you can run them year round.

The only reason I choose the Rotella T6 is because the 0W40 grade is commonly available in it, whereas all the others are usually only seen as a 5W40. 5W40 will cover almost any normal situation, so no real need for the 0W40 most of the time, but on the coldest days of winter it lets the engine spin a little faster on the starter. I have started mine (with great difficulty) unplugged down to about -35F at 5000' altitude. In that situation every single RPM of cranking speed helps. But in general there is no other advantage vs the 5W40.

Conventional oils are worse in every respect, they are not much cheaper and don't protect the engine nearly as well and need to be changed more often. Good ones like Delo 400 or Rotella T4 will do a decent job but there's just no real argument in favor of them, they have no advantage, not even cost, since shorter drain intervals are required. Synthetics perform better in both cold AND hot temperature extremes, have better film strength, and do a much better job controlling deposits.

I would stick with the synthetic but switch from your 10W30 to 5W40.

Another point: synthetic 5W40 is exactly what Volkswagen calls for in more modern TDI engines, which are mechanically identical to the D24 and D24T. No doubt they would have called for it for the D24 family too if good synthetics had been widely available back when the engines were first built.

[Goteborg Vapenfabrik]

Ive been using Amsoil synthetic lubricants in Volvos for twenty years. Its quality is second to none. Amsoil doesn't use misleading advertisements. All its claims are backed up by scientific research. It's not available at big box stores. Ordering oil is no different from ordering parts. You aren't going to buy any parts for a D24/T at a big box store anyway. Synthetics are superior to conventional oils. Amsoil is the first in synthetics. Im sending you a private message with my contact information if you would like to know more. It cost a little more, but its absolutely worth it.

[jpliddy]

hi i have been using a millers 10/40 semi synthetic oil for last 20 years oil and filter changed every 6000 miles over here .
hope its ok and car will survive till they get these of the road here in uk !

[RedArrow]

I use Mobil 1 oil, every 5000 miles,
5W40
Turbodiesel Truck fully synthetic engine oil and very satisfied with it.

Many years ago, it wasn`t always easy to find on the shelves but by now I always see it at Autozone, gas stations, Walmart etc, Advance Auto Parts etc.

The cost of our oil change (without the filter) is gonna be around 50 dollars because you need to buy 2 gallons... and, you`ll still have approximately 1 quart of new oil left, good for top-ups on the road, if needed. That`s about 1usd `spent` on oil for every 100miles.

https://www.walmart.com/ip/Mobil-1-5...RoCKAUQAvD_BwE

Be careful, the Walmart link is misleading, the oil is 5W40 but it looks as if it was 15w40

I bet this Mobil 1 is good enough to use for even up to 8000miles but I guess this oil isnt too expensive to even make experimenting worth it. And you love your d24 and you want it to collect a huge amount of miles, right?

Also, in case your car `eats` some oil (some cars do use oil up to a quart/1liter per circa 1000miles), then by the end of your 5000 miles you actually have will have refreshed your oil substantially, just by regularly adding oil as car consumed it... (by topping up at each check-up at the dipstick) ...so... in 5000miles you actually replaced up to 5quarts of the total capacity of your engine which is 7 quarts...
something to consider and add in, for some unlucky owners LOL.

((So in my opinion, for those who have their cars consuming motor oil, oil changes don`t have to be religiously 5000miles. The `older, used part` of your motor oil regularly gets diluted/mixed into something healthier as you go, every time you top up the system with some fresh oil. REGULAR CHECKUPS are still a must! Actually it is only the level checkup that is able to tell you what is going on inside, oil quantity-wise, so... I would say: pop that hood before your trips or at least once every 500miles at the most. Most of the existing running d24 d24t engines are well over 25-30years old today. ))

PS
it seems these engines can lose a lot of oil at and around the valve cover, especially if the gasket is too old, or a wrong kind (2-piece cork gasket is really bad) or in case the top cover got installed incorrectly, too loose too tight or misaligned/bent etc by wrong&uneven torque values, wrong tightening sequence etc. Everything counts
I have successfully reused the Goetze valve cover gaskets before so it is definitely worth the extra bucks! About triple the price of the cork junk 2-piece ones BUT IT`S TONS BETTER and seals really really well.