Consider that autobarn/repco sell this for $36-7 RRP, and it's quite a decent saving!
Castrol GTX 15W-40 $19.95 @ Supercheap Auto
![](https://files.ozbargain.com.au/g/38.jpg)
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I don't know to be honest, i'd like to see other opinions. Yes i saw that special too, but i like to stick with consistent oils in my cars.
GTX is the bottom range mineral oils for 90s cars.
Magnatec is the semi synthetic mid range and Edge is the usually fully synthetic premium range.So no. Hope that helps.
so in general, synthetic > mineral?
10W-40 is better than 15W40.
Go the 10W-40 if you have a reasonably new car.Not necessarily for a reasonable new car. 10W-40 is still a better option for older cars too.
Well the most engine wear/damage occurs at cold starts, so you'd want better protection (higher viscosity) at cold temperatures for older vehicles, no?
The higher the viscosity, higher probability that the oil goes down to the engine oil pan completely as it tends to be heavier than semy synthetic and synthetic oils. The idea wiht low viscosity oils is to avoid most of oil going down to the oil pan and let some sticked inside the engine so when you do a cold start the engine pieces are still covered with oil and prevent wear/damage. I would like to say that I'm not an expert, just another human being trying to maintain the car by myself. :)
Thinner oils pump quicker though, so the lower number actually works in your favour at start-up. As mentioned though semi-synth and synth are modified to have bette surface adhesion, reduced shear,etc and are superior to mineral oils. Only downside to 10W-40 over 15W-40 is worn engines may consume a bit too much of the thinner oil… In a decent new car I would actually run 5W-40/5W-50
Its also important though to consult with your cars manual and choose the viscosity that suits the temperature extremes your car will be exposed to..
Online price $19.95 + $10 postage!
Not available at my local Supercheap Auto at this price of $19.95.It is in the latest catalouge (came out today), may be worthwhile calling your local store?
Is this equivalent to Castrol GTX 3? Currently use GTX3 for my 2001 Corolla. This sounds like a pretty good deal.
Castrol should have a product selector on their website
Is this oil better than the Magnatec 10W-40? If so, this is not a bargain, as I bought that for $30 with oil filter included in Repco. This week Repco had the same for $20 without oil filter.