Shell Rimula is a capable alternative to Delvac. In Egypt, driving conditions are not easy on engines; extreme day temperatures north of 38 celcius, sometimes crossing 40 for several days in a hot wave, dusty roads, "stop 'n go" traffic, "5000 ppm" Sulphur in diesel, you can fill-in the rest. Yet, Delvac and Rimula are praised by truckers for holding up in even worse cases as with dump trucks easily hitting 1m kilometers on the odometer for many. I'm in the agro-business, and truckers experience are a lot better on-ground benchmark than UOAs, and marketing claims. So we can take that as a donut of trust not printed on the jug.
Rubia 8900 10W-30 has stringent approvals such as Mack EO-O PP, MB 228.51 and VDS-4. Actually, I have little idea about its performance, we have it on the shelves, however, it's very rare to find people even talking about it.
For almost the same price, Delvac 1300 Super 10W-30 is very stout and is well praised. Both should be fine.
Usually, there is less VIIs in 10W-30 than 15W-40 because of less spread between cold rating and operating temperature grade. In case of temporary or permanent shear, 10W-30 will be more shear-stable (loss of less HT/HS viscosity) than 15W-40, but 15W-40 will retain slightly higher viscosity because it was formulated from a higher viscosity base oil even though it sheared more. Think of it this way: 10W-30 HT/HS started fresh at 3.5, for instance, and ended up to 2.8, and 15W-40 started at 4.1 and ended up to 3.1, so even though it has less shear stability, it still has higher HT/FS than 10W-30.
So a higher winter rating is a good indicator of HT/FS (base oil HT/HS without VIIs contribution to viscosity).
Both will offer solid film at the end as long it's higher than HT/HS of 2.6 after temporary or permanent shear takes place with higher base oil viscosity of 15W-40 and the thicker 20W-50 offering the necessary cushion for higher temperature applications. Let the ambient and oil temperatures on the dashboard decide which one will go in the sump. Not the OEM committed to CAFE. Going below 2.6 for HT/FS (HT/HS after shear) and things will go exponential for the worse.
Don't worry much about cold start, even 20W-50 will be good in your climate.