The debate of frequent changes vs extended drains shows up everywhere. The main point that everyone seems to make is the effective cost savings you would attain from extended drains. So it got me wondering...is it really saving you money if you're topping off with quarts?
Let's take this example:
Person 1 changes oil A every 5k miles. Each change costs him $15 in oil (using Autozone QSGB special). For 15,000 miles, he would need 3 changes. 3x $15 = $45.
Person 2 changes oil B every 15k miles. Each change costs him $33 in oil (using Autozone M1 EP special). For 15,000 miles, he would need 1 change. 1x $33 = $33.
Now let's give these 2 guys the same car--a beater that consumes 1/2 qt every 3k miles.
By the time Person 1 hits 5k miles, he would have lost a tad under 1 quart. While he may need to top it off to go on, it's dismissed because he goes in to change out his oil entirely, putting in a fresh batch of oil. This is repeated 3 times.
For Person 2, by the time he hits 5k miles, he would have lost a tad under 1 quart just like Person 1. To go on to continue his extended drain, he would need to top it off. He goes out to buy a quart of M1 EP -- $7/qt (and I'm being generous here). After another 5k miles, he needs to top it off again, going out to buy another qt of M1 EP, spending another $7. At the end of his last 5k miles, the car again consumed a little under 1 qt. Instead of topping it off, it is dismissed because he has reached his 15k mile oci and will put in a fresh batch of oil.
Now calculations...
Person 1 spends 3x $15 = $45
Person 2 spends 1x $33 = $33 + $7 (first top off) = $40 + $7 (second top off) = $47 total in the end.
Is extended drain saving money when $47 > $45?
Of course if the car consumes no oil then extended drains would be the obvious choice, but from the consensus that a good chunk of cars out on the roads need top off oil, how are they saving money?
Let's take this example:
Person 1 changes oil A every 5k miles. Each change costs him $15 in oil (using Autozone QSGB special). For 15,000 miles, he would need 3 changes. 3x $15 = $45.
Person 2 changes oil B every 15k miles. Each change costs him $33 in oil (using Autozone M1 EP special). For 15,000 miles, he would need 1 change. 1x $33 = $33.
Now let's give these 2 guys the same car--a beater that consumes 1/2 qt every 3k miles.
By the time Person 1 hits 5k miles, he would have lost a tad under 1 quart. While he may need to top it off to go on, it's dismissed because he goes in to change out his oil entirely, putting in a fresh batch of oil. This is repeated 3 times.
For Person 2, by the time he hits 5k miles, he would have lost a tad under 1 quart just like Person 1. To go on to continue his extended drain, he would need to top it off. He goes out to buy a quart of M1 EP -- $7/qt (and I'm being generous here). After another 5k miles, he needs to top it off again, going out to buy another qt of M1 EP, spending another $7. At the end of his last 5k miles, the car again consumed a little under 1 qt. Instead of topping it off, it is dismissed because he has reached his 15k mile oci and will put in a fresh batch of oil.
Now calculations...
Person 1 spends 3x $15 = $45
Person 2 spends 1x $33 = $33 + $7 (first top off) = $40 + $7 (second top off) = $47 total in the end.
Is extended drain saving money when $47 > $45?
Of course if the car consumes no oil then extended drains would be the obvious choice, but from the consensus that a good chunk of cars out on the roads need top off oil, how are they saving money?