It sure would be nice when a mechanic who finds burned lifters also stops to think about why they might have burned; rather than just advising that they be replaced. But apprently, that's too much to expect in today's world. It is abnormal for lifters to burn (on any car where this happens; whether it be a Ford or a Saturn). Yes, it happens because of insufficient lubrication; but if the source of the insufficient lubrication is not found and repaired; the new lifters are soon going to look like the old ones did, and other problems (like sticking valves) are also likely to develop.
There are several reasons why engines develop insufficient lubrication. One is because certain GM and Toyota engines built in the last decade have flawed cooling system designs; which develop hot spots in the cylinder heads near oil passages. The oil in those locations then overheats and forms high temperature sludge; which flows through the motor and clogs up oil passages, lifters and galleries. And this sludge restricts the oil flow to the cylinder heads; which critically need a plentiful oil supply in order for their moving parts to be properly lubricated. So the camshafts, lifters, and valve stems end up suffering from lack of lubrication. The oil pump can also be damaged by this. I think you can see from this explanation how futile it would be to replace damaged cylinder head parts in such a system; without correcting the cause of the damage. I also feel that cars with this type of design flaw will not be long lived, regardless of the degree of repair they are given.
Three other possible causes of burned lifters are either using an unsuitable oil type, such as non detergent or single weight oil (which I expect is far more commonly used in South America than in the USA), or using too lightweight an oil grade, or not changing both the oil and oil filter at manufacturer's recommended intervals. Those abusive practices will also fill the engine with sludge and clog up oil passages.
So much for the theory: The real question is what to do about it now. Since there is considerable likelihood of other damaged parts inside the motor, and the oil pump and oil passages throughout the motor are probably affected; I personally would not bother trying to repair bits and pieces as they become known. A sludged up motor of this type is basically a time bomb waiting to explode. Some backyard mechanics might decide to try cleaning the motor out by running solvents and cleaning compounds through the oil. This could be helpful; but it also could break loose large quantities of gunk which might totally block a vital oil line, and thus lead to the sudden death of the motor. In my view, there is no point in chasing symptoms without at least restoring normal oil pressure and volume. And that probably cannot be done effectively and safely without tearing the whole motor down.
Beacuse major engine work is both extremely labor intensive, and also requires precision machining operations which are probably not available in Peru; I would recommend replacing the motor with a properly remanufactured one; or with a known good used engine. It might be necessary to have the replacement engine shipped there from a salvage yard or a remanufacturer in the US. For either a properly remanufactured or a good used engine; I would contact (www.hiperformer.com) They are a top quality engine remanufacturer in Spokane, Washington, who is also connected to a network of salvage yards all across the US. Their prices and quality cannot be beaten; and they are able to ship motors anywhere at very competitive rates. Please bear in mind that their remanufactured engines have all new internal parts; but require the transfer of external sheet metal parts like oil pans, valve covers, and some ignition,.exhaust and fuel system parts from your old motor.
The other options would be to try to flush the sludge out and risk the consequences; or to buy a different vehicle.
I can recommend some formulas to clean out the sludge; but please bear in mind what I wrote about possible consequences, and about nonsustainable engine designs. If you would like additional details, please respond by clicking the "answer this question" button; which will keep all the responses in this original thread.