Late reply but better than never.

1. Although you can use weighted 40 syntium, I would not recommend it. Weight 30 is lighter and have better FC. Unless you constantly runs at high speed, using 30 lube would perform much better than 40. If you constantly, I really mean constantly runs at above 140km/h, 40 lube might be beneficial. Note that Preve does not have very strong torque at below 2K rpm, using 40 will definitely makes it heavier and worse.

2. All lube are supposed to service at 5K mileage regardless of FS, Semi or mineral. There are exception such as specifically mentioned High-Mileage lube, higher range cars with bigger lube storage and exceptional filteration system. Otherwise in reality on our weather and driving condition, even FS, IMO, should only go max 7K mileage before addictives wear out. Recommended 5K tho to be safe and perform optimally. If you wanted to follow the 10K service interval, only using FS should you even try to last that long. By then even FS addictives might have worn out and risk miniscule damages to engine. But then proton say can last 10K, if their engine are made to last optimally that for long term if continually using 10K interval even for FS.

In truth, all lubes, mineral, semi and fs have a garanteed 5K life for its addictives. After 5K, its up you. Most ppl say can use up to 10K in order to justify the much higher cost of using FS. With our dusty, hot and humid weather along with our road and traffic conditions, at most FS can withstand is abt 6-7K mileage. Addictives would have been mostly worn by then.

Overseas, some can go much longer due to one of the reason

1. Using specific HIGH MILEAGE FS. (These FS were designed to go for high mileage unlike normal FS).
2. Bigger CC car with much better filteration system. Bigger lube tanks do makes a difference in how long we use the lube but that have to coupled with corresponding higher quality filteration system. Thus those luxury bigger cc cars might be able to go up to 10K for FS. Not our medium and small sedan.

IMO, I would never exceed 6K at most for FS. Yes you can still use it but after years only you can see the damage, etc. miniscule damage to bore wall, sludge buildup, rust, etc. That happens when addictives worn out. Even manufacturers makes mistakes sometimes in recommending longer usage as had happened even to some luxury brands (Japan) in US. After a couple of years, sludge buildup cause a major headache and company have to backtrack and shorten the service interval.

Do note our standard size oil filter if clog up will allow bypass, that means no filteration after that, everything goes thus our engine can still work even if filter clog up after 5K mileage.

Question is do you want to change lube BEFORE addictives and protection wear out or AFTER it wear out. Once addictives start to wear, protection and lubrication will be greatly reduce, after that only you change.....you can imagine the damage buildup if you intend to keep your car for long. I prefer to change at 5-6K interval for FS BEFORE addictives start to greatly wear out. If any of you mentioned its too expensive to do that.....by all means change to semi or mineral and service every 5K, your engine will be cleaner than using FS for 10K, trust me on that.

Actually there is no difference with 10W and 5W for our weather. THAT is WINTER weather rating. Its the number behind the W that matters, ie 5W30, 10W30, 5W40, etc. Essentially both 5W30 and 10W30 performed the same in our weather, both 10 and 5 are sub-zero temperature, so unless Malaysia start snowing, don't be bother with it.

30 and 40 perform differently with 40 being thicker and more suitable if you constantly speed on highway. 30 being lighter suffice for daily drive and it's actually much more economical in FC than 40 besides giving better torque. However speeding means heat in engine and if you constantly runs for long on highway at high speed, 40 will be more suitable albeit with sacrifice of FC and a bit of low end pickup.

Once engine got older and bore gap becomes larger (ie 100-200K mileage), your initially thickness might not suffice. One of the reason the older engine using 40 or 50 weighted lube.

Persona recommended lube is 40, probably becoz of its hot engine. The better cooling system of CPS probably allow Proton to suggest 30, FC saving and balance ride. FS do makes a slight difference as it can take absorb more heat before breaking up but frankly, unless we're racing constantly , the higher heat rating of FS makes no diffence for daily drivers.

Cost cutting? Subpar sensor?

Why the heck are you using a weight 50 lube? Too heavy for the engine, does not good for your FC and pickup power. Even tho its fully syn, you're better off using syn 800 weight 30 or 40 semi syn.

Unfortunately Proton Edar especially CoSE stock only Syn 1000 W50 for FS. If you want 40 or 30, only semi available. Thats why some ppl without the knowledge opt for the FS without realising the weight actually reduce the PICKUP quite noticeably.

W50 is good for older cars where the piston wall bore gap has worn and gap are larger thus require thicker lube. Its also good for cars that run high speed with very hot engine and its good for extreme hot weather (Saudi, etc). For Preve and other newer proton, I doub't we'll ever need 50 weighted lube unless its old.

Even tho its FS, the lube is too thick for balance FC saving and pickup power, so for me, its not worth it to change to weight 50 FS coz the the car will USUALLY be heavier on pickup and does not help in FC in order to reduce 1 service.

oh btw 5W does not mean better startup. There is no difference in 0W, 5W and 10W as it is winter rating, sub zero temperature, so 10W will act the same as 5W in our morning startup.

However the bigger difference in the gap between winter rating and original rating (5W40m, 0W40), more viscosity addictives is needed thus when it wears out, it will have bigger affect on your viscosity changes. One of the many reason I recommend lube changes BEFORE addictives runs out. When you do that, then any negative effects of caused by worn addictives is render irrelevant.

This post has been edited by Cavino: Jul 13 2012, 04:29 PM