i see there are alot of questions on oil, so with the power of my brain, college experiments, and experience united, here's my 2 cents on the matter,!
just my opinion on synthetic oil on turbo cars, is that turbo's heat the oil more then their N/A counterparts and sythetic oil wont break down as fast a conventional oils, and semi-synthetic is a little misleading because it is conventional oil with more additives, and detergents, which makes it better at reducing friction and keeps your engine cleaner, but it still breaks down like conventional oil.
i worked at an import shop for awile and i seen alot of audi and vw 1.8l turbo engines fail because the turbo cooked the oil and people who drive imports i've noticed are a bit stingy and typically buy mobil conventional oil and go 5000-7500 miles between oil changes, at which point the oil has lost its weight.
stay with me now oil weight is modified by adding an viscosity modifying additive that allows the microscopic paraffin strands/coils that oil is made of, separate at lower temps, but also rejoin at higher temps. so lets use 5w20 as an example. it is a strait 20 oil base, when the oil is cold it acts like strait 5w oil, which is all fine and dandy, but after so many heat cycles the viscosity modifying additives will start to separate from the oil, which is what happens when the oil breaks down, so now your 5w20 can act more like 5w10 or even strait 5w as the microscopic paraffin coils/strands no longer rejoin. also the hotter you get the oil the faster the viscosity modifying additive will separate.
what makes synthetic oil better is those microscopic paraffin wax coils/strands are now made of a synthetic compound that is less prone to heat/failure. (i think its more like a plastic)
another thing i havent mentioned yet is another job of motor oil is to collect deposits from your engine along with whatever sneaks past the piston rings, but as engines are quite efficient now i think that oil breakdown is more of a factor then it was before when oil appeared dirty at 3k and now it can still apear clean after 5k.
there are 2 ways to change oil, in my opinion, that are the best for your motor.
1. use cheap conventional oil and change every 3,000miles (best for older dirty engines, like my rx7-f-150)
2. use full synthetic oil and change it every 5,000miles (however if you do alot of highway driving the oil is subject to less heat cycles/per miles so its up to you to figure out an oil change strategy that best suits you, but i still wouldnt go past 7,500miles)
:bonus info-coolant temp senders use paraffin wax in a closed chamber and a contact plate on top so as the paraffin expands it pushes the contact plate further up the resistor to change the value that the pcm or gauge reads.
:more bonus info-oil that has less of a difference in weight number will be less prone to break down. example 5w20 is better than 5w30 because 5w30 will have more expanding coils. thats why race cars use strait oil such as 30w.
just my opinion on synthetic oil on turbo cars, is that turbo's heat the oil more then their N/A counterparts and sythetic oil wont break down as fast a conventional oils, and semi-synthetic is a little misleading because it is conventional oil with more additives, and detergents, which makes it better at reducing friction and keeps your engine cleaner, but it still breaks down like conventional oil.
i worked at an import shop for awile and i seen alot of audi and vw 1.8l turbo engines fail because the turbo cooked the oil and people who drive imports i've noticed are a bit stingy and typically buy mobil conventional oil and go 5000-7500 miles between oil changes, at which point the oil has lost its weight.
stay with me now oil weight is modified by adding an viscosity modifying additive that allows the microscopic paraffin strands/coils that oil is made of, separate at lower temps, but also rejoin at higher temps. so lets use 5w20 as an example. it is a strait 20 oil base, when the oil is cold it acts like strait 5w oil, which is all fine and dandy, but after so many heat cycles the viscosity modifying additives will start to separate from the oil, which is what happens when the oil breaks down, so now your 5w20 can act more like 5w10 or even strait 5w as the microscopic paraffin coils/strands no longer rejoin. also the hotter you get the oil the faster the viscosity modifying additive will separate.
what makes synthetic oil better is those microscopic paraffin wax coils/strands are now made of a synthetic compound that is less prone to heat/failure. (i think its more like a plastic)
another thing i havent mentioned yet is another job of motor oil is to collect deposits from your engine along with whatever sneaks past the piston rings, but as engines are quite efficient now i think that oil breakdown is more of a factor then it was before when oil appeared dirty at 3k and now it can still apear clean after 5k.
there are 2 ways to change oil, in my opinion, that are the best for your motor.
1. use cheap conventional oil and change every 3,000miles (best for older dirty engines, like my rx7-f-150)
2. use full synthetic oil and change it every 5,000miles (however if you do alot of highway driving the oil is subject to less heat cycles/per miles so its up to you to figure out an oil change strategy that best suits you, but i still wouldnt go past 7,500miles)
:bonus info-coolant temp senders use paraffin wax in a closed chamber and a contact plate on top so as the paraffin expands it pushes the contact plate further up the resistor to change the value that the pcm or gauge reads.
:more bonus info-oil that has less of a difference in weight number will be less prone to break down. example 5w20 is better than 5w30 because 5w30 will have more expanding coils. thats why race cars use strait oil such as 30w.
