Originally Posted By: Tech819
This is from the Pennzoil Q and A take it for what you want.
6. I’m interested in making a custom blend for my vehicles. Preferentially starting with Rotella T6 5W-40, as it’s in the family, but wanting something a bit closer to 5W-30. Rotella as it’s in the family, and a strong oil, but if needed, Platinum Euro 5W-40 could be considered as a starting point. I would like to blend it down to a 5W-30 using Platinum 5W-20, so that I will end up with a 5W-30 with a little more anti-wear additive than the typical 5W-30. Are there any problems doing this, and will the results be as I expect them to be?
The physical results may be very much as you expect i.e. viscosity is likely to be predictable following well known physical laws however the chemical effects are highly unpredictable. Wear performance is not dictated solely by the amount of wear protecting additives in an oil, the efficacy (effectiveness) of the additives must also be considered. Efficacy can be negatively impacted by changing the balance of a formulation package. The approach you suggest could conceivably result in poorer performance, I would recommend choosing a single tier of product, and Pennzoil Platinum has been designed to offer complete protection including unsurpassed wear performance.
Of course Pennzoil/Shell is going to tell you just to use their products and not risk mixing. If you could make better 5W30 by mixing 40 and 20, then everyone would do it and their 30 would suffer. People switch oil brands all the time and grades too. The left over oil would still be stuck to parts of the engine and mixing always occurs. My car takes 4L to fill but if rebuilding and bone dry, will take 5L. So no matter how well the engine is drained, you always have around 1L left in the engine, stuck to various parts that won't drain.
This is from the Pennzoil Q and A take it for what you want.
6. I’m interested in making a custom blend for my vehicles. Preferentially starting with Rotella T6 5W-40, as it’s in the family, but wanting something a bit closer to 5W-30. Rotella as it’s in the family, and a strong oil, but if needed, Platinum Euro 5W-40 could be considered as a starting point. I would like to blend it down to a 5W-30 using Platinum 5W-20, so that I will end up with a 5W-30 with a little more anti-wear additive than the typical 5W-30. Are there any problems doing this, and will the results be as I expect them to be?
The physical results may be very much as you expect i.e. viscosity is likely to be predictable following well known physical laws however the chemical effects are highly unpredictable. Wear performance is not dictated solely by the amount of wear protecting additives in an oil, the efficacy (effectiveness) of the additives must also be considered. Efficacy can be negatively impacted by changing the balance of a formulation package. The approach you suggest could conceivably result in poorer performance, I would recommend choosing a single tier of product, and Pennzoil Platinum has been designed to offer complete protection including unsurpassed wear performance.
Of course Pennzoil/Shell is going to tell you just to use their products and not risk mixing. If you could make better 5W30 by mixing 40 and 20, then everyone would do it and their 30 would suffer. People switch oil brands all the time and grades too. The left over oil would still be stuck to parts of the engine and mixing always occurs. My car takes 4L to fill but if rebuilding and bone dry, will take 5L. So no matter how well the engine is drained, you always have around 1L left in the engine, stuck to various parts that won't drain.
