In America, I believe the FDA has not approved the combined use of Avobenzone with Zinc Oxide or Titanium Dioxide together in the same sunscreen. I don't see why Oxybenzone, Avobenzone, and Memorex SR can't be combined, perhaps too many chemicals in one lotion imposes unforesen harm. This is why in order to raise the SPF and keep the sunscreen safe by FDA standards, it's either Avobenzone or sacrificing a little UVA to up the UVB.
During winter, the UVB threat is lower than summertime, but the UVA threat is merely unchanged, so use this in winter. I hope this helps.