115 million gallons in our Wholesale segment, offset by increases of 99 million gallons and 12 million gallons in our GDSO and Commercial segments, respectively.
Gross Profit
Our gross profit was $178.0 million and $239.9 million for the three months ended June 30, 2021 and 2020, respectively, a decrease of $61.9 million, or 26%, primarily due to less favorable market conditions in our Wholesale segment, partially offset by improved margins in our GDSO segment, largely in station operations due to an increase in activity at our convenience stores but also in gasoline distribution due to an increase in volume.
Our gross profit was $323.1.0 million and $385.7 million for the six months ended June 30, 2021 and 2020, respectively, a decrease of $62.6 million, or 16%, primarily due to less favorable market conditions in our Wholesale segment. Lower fuel margin (cents per gallon) in our GDSO segment also contributed to the year-over-year decrease in gross profit, partially offset by an increase in fuel volume and in station operations due to an increase in activity at our convenience stores.
Results for Wholesale Segment
Gasoline and Gasoline Blendstocks. Sales from wholesale gasoline and gasoline blendstocks were $1.5 billion and $0.5 billion for the three months ended June 30, 2021 and 2020, respectively, an increase of $1.0 billion, or 172%, due to increases in prices and volume sold. Our gasoline and gasoline blendstocks product margin was $23.5 million and $58.3 million for the three months ended June 30, 2021 and 2020, respectively, a decrease of $34.8 million, or 60%, primarily due to less favorable market conditions, largely in gasoline but also in gasoline blendstocks. During the second quarter of 2020, there was a significant recovery in the supply/demand imbalance that occurred at the end of the first quarter of 2020 caused by the COVID-19 pandemic related demand destruction and geopolitical events. The forward product pricing curve flattened which positively impacted our product margins in the second quarter of 2020.
Sales from wholesale gasoline and gasoline blendstocks were $2.3 billion and $1.5 billion for the six months ended June 30, 2021 and 2020, respectively, an increase of $0.8 million, or 52%, primarily due to an increase in prices, partially offset by a decline in volume sold. Our gasoline and gasoline blendstocks product margin was $39.9 million and $67.8 million for the six months ended June 30, 2021 and 2020, respectively, a decrease of $27.9 million, or 41%, primarily due to less favorable market conditions largely in gasoline but also in gasoline blendstocks. During the second quarter of 2020, there was a significant recovery in the supply/demand imbalance that occurred at the end of the first quarter of 2020 caused by the COVID-19 pandemic related demand destruction and geopolitical events. The forward product pricing curve flattened during the second quarter of 2020 which positively impacted our product margins.
Crude Oil. Crude oil sales and logistics revenues were $17.0 million and $9.0 million for the three months ended June 30, 2021 and 2020, respectively, an increase of $8.0 million, or 88%, due to an increases in prices. Our crude oil product margin was ($3.3 million) and $9.2 million for the three months ended June 30, 2021 and 2020, respectively, a decrease of $12.5 million, or 136%, due to less favorable market conditions. Our crude oil product margins in the second quarter of 2020 benefitted from more favorable market conditions, including the flattening of the forward product pricing curve.
Crude oil sales and logistics revenues were $33.9 million and $15.5 million for the six months ended June 30, 2021 and 2020, respectively, an increase of $18.4 million, or 119%, due to an increase in prices. Our crude oil product margin was ($7.8 million) and $4.7 million for the six months ended June 30, 2021 and 2020, respectively, a decrease of $12.5 million, or 266%, due to less favorable market conditions. Our crude oil product margins in the first six months of 2020 benefitted from more favorable market conditions, including the flattening of the forward product pricing curve during the second quarter of 2020.
Other Oils and Related Products. Sales from other oils and related products (primarily distillates and residual oil) were $474.9 million and $280.8 million for the three months ended June 30, 2021 and 2020, respectively, an increase of $194.1 million, or 69%, due to an increase in prices. Our product margin from other oils and related products was $13.3 million and $44.5 million for the three months ended June 30, 2021 and 2020, respectively, a decrease of